The following is a list of named demonstrations we can provide.
We use an internal letter-number scheme for organization and requests.
For reference, we also provide the Physics Instructional Resource Association (PIRA) Demonstration Classification Scheme (DCS) code in brackets.
This page is under construction. If you are looking for a particular demo, there may be info here.
Replica of metric rod stored in Paris, length 1m.
A student’s height is measured once standing up and once laying down. The difference in height between the two measurements is then shown.
A number of unit masses are provided to let students get a hands-on feel for various units.
A modulated laser strikes a beam splitter. The reflected laser light travels through a lens to a photodetector. The transmitted laser light travels across the lecture hall to a front surface mirror, then back through a second lens focused on a second photodetector. With a path length difference of about 4 meters, one should expect a 12 ns phase delay (3.3 ns/m or
Duplicate - see B65 or B106 for specific demos
A plush apple is suspended from a rod at one end of the lecture hall. The apple is released and begins falling at the same instant a spring gun fires a golf ball at it from the other end of the lecture hall.
A cart moving in a straight line shoots a ball straight up. The ball follows a parabolic path and is caught in a large funnel on the moving cart. This demonstration uses the large track which can only be used in room 26-100. This demonstration shows that the velocity in the x direction stays constant during parabolic motion.
The free fall of a coin and feather in a vacuum are compared. This demonstrates that without air resistance all objects on the surface of Earth fall with the same acceleration (9.8 m/s^2).
!Safety Concerns! : projectile
Using an adjustable angle spring gun, the trajectory of a ball can be observed. Its relationship to the launch angle can then be determined. The point at which the ball will land for a given angle can be calculated and then shown.
!Safety Concerns! : fluid
Water passing in a parabolic path through hoops. When the entire assembly is tilted, the water will still go through the hoops.
Ball bearings of different diameters and masses are dropped in a glass container filled with corn syrup. The time it takes to fall a set distance is measured and the terminal velocity is measured. This is shown with a camera that can be projected onto the screens in the room. It is shown that spheres with larger radii have larger terminal velocities.
!Safety Concerns! : gun
A pair of spinning wheels 1.5 meters apart is placed in the path of a bullet. The gun is fired with the wheels stationary for a reference position. The gun is fired again with the wheels spinning at a known speed. The difference between the reference hole and the second hole is compared. The bullet speed can then be determined.
!Safety Concerns! : gun
On the same apparatus, two cards wrapped with thin insulated wire are placed in the path of the bullet. The distance is the same. The wires are broken by the bullet which gives a start and stop pulse triggering a digital timer.
!Safety Concerns! : gun
The start and stop pulses also go to a storage scope giving two pulses on one sweep with which the bullet speed can be determined.
!Safety Concerns! : projectile
A ping pong cannon is fired into a pendulum hanging from wires. The mass of the pendulum and ping pong is measured. Measurement of the displacement of the pendulum then yields the velocity of the ping pong.
Demonstrates motion with constant acceleration.
Two wooden apples are dropped from different heights. The first from 3.2m, and the second from 1.6m. The time is measured electronically and g is calculated.
!Safety Concerns! : strobe
Using a stroboscopic picture of a ball falling near a meter stick, the acceleration of the ball is measured. The picture is shown on the screens in the room.
!Safety Concerns! : strobe
The 5-meter air track is placed on the lecture tables so that it makes an angle with the horizontal. A cart slides down the track and a stroboscopic photograph of its motion is made. This has to be photographed before the lecture.
A weight is attached to a cart on the air track via a string and pulley. The velocity of the cart is measured with digital timers as the weight falls. This demonstration can also be performed with heavy carts.
Two wooden boards 1 m long, mounted one above the other, are hinged together at one end. A small cup is mounted near one end of the upper board with a tee for a ball on the end. The top board is propped up with a dowel and a ball is set on the tee. When the dowel is quickly pulled away, and the hinged board has completed its fall, the ball ends up in the plastic cup. This shows that the board has moved farther than the ball in the same period of time. Different balls can be used to show that it is independent of the ball's mass.
Two air tracks, one level and one at an angle of ≅6.5°, form an elementary Atwood machine. Each track has an air cart linked together by a string. The string rides on a pulley between the air tracks. The horizontal cart is released at the beginning of the track and the velocity of the cart is measured using the sonic sensor and the lab quest. Acceleration of the carts is determined and compared with theory.
Demonstrate Newton’s 2nd Law for an Atwood Machine system. Demonstrate both static and dynamic equilibrium.
Demonstrate Newton’s 2nd Law for an Atwood Machine system. Demonstrate both static and dynamic equilibrium.
This classic experiment combines the effects of linear and angular accelerations. A string carrying two, weight holders passes over a large ball bearing mounted pulley. The weight holders have appreciable mass, the accelerating force being provided by a small rider added to one of them. The acceleration of the system is small due to the large inertia of the pulley and the heavy masses of the weight holders. The linear and angular inertias of the system are comparable. The pulley has a simple geometric shape so that the Moment of Inertia can be easily calculated. The heavier weight holder is held in place on a platform so that its starting height can be carefully measured. The platform is dropped to start the experiment and the system accelerates. The weight holder falls until it strikes a fixed weight platform at the bottom of the support column. The acceleration is calculated from the times taken to traverse this distance. Repeating the experiment with other weight differences gives the data needed to calculate the effect of friction and the acceleration due to gravity.
The components of a cart's weight normal and parallel to an inclined track are balanced with masses hung over pulleys. The track can then be removed, leaving the cart stationary.
A large scale replica of the Cavendish experiment can be shown to the class for a better visualization of how it worked.
Two balloons are hung in a sealed box. One is filled with air and hung with a string from the top of the box; the other is filled with Helium and attached with a string to the bottom of the box. When the box is accelerated, the Helium balloon moves in the direction of motion while the air-filled balloon moves in the opposite direction.
Three balls travel down three different trajectories. The ball on the catenary reaches the bottom first.
The Bricklayer's Lament, a comedy bit told by Gerard Hoffnung at the Oxford Union recorded by the BBC on December 4th, 1958. Cassette Tape contains 3 copies of varying quality.
Weights are attached to a vertical spring. As each weight is added, the displacement of the spring is measured. If g is known, the spring constant is determined, or if the spring constant is known, g can be calculated. Various size springs are available.
A series of springs with known spring constants are used to illustrate that the tension is the same in all the springs by measuring their extensions.
This demonstration shows that two identical springs in parallel move the same distance those two identical springs placed in series if the ratio of the masses they support is 4:1
Equal weights are added to a pull-type spring scale. The deflection of the scale is shown to be linear. Shown with TV system.
This is a network of 3 strings and 2 springs in which cutting a string that supports a weight results in a rise of the weight at equilibrium.
A wire hung from a mount is weighted with 1 kg weights. As more weights are added, the wire stretches and eventually breaks. A small mirror gradually tilts as the wire stretches. This change is shown on the wall with a laser beam reflecting off the mirror.
Two spring setups are compared to explore the concept of tension in a spring in equilibrium.
The coefficient of static friction is measured by placing a wooden block on an incline and adjusting the incline until it slips. This can also be done with plastic bins of different weights but the same surface area, a rubber hockey puck, a plastic bin, and two pieces of wood with the same mass but different surface areas. The angle is determined with a digital readout level or by trigonometry.
A block of wood with three different surfaces is placed on a 2m. Wooden plank. The plank is set at an angle that is measured with a mounted protractor. A length of string is attached to the back and run over a pulley. Weights are added to the string until the block slides. The coefficient of static friction can then be measured.
Demonstrates static and kinetic friction between two surfaces.
A wood plank is leaned against a vertical board. The angle at which it falls can be measured and compared with a calculation based on the coefficient of static friction. This can also be done with a ladder against the wall.
The static Friction of several turns of rope around a metal bar is measured. It is shown that the amount of friction increases significantly with each wrap of the rope.
This consists of a single air cart on an air track with a timer. The demonstration shows that the distance an air cart moves on a nearly frictionless surface is proportional to the KE of the air cart.
It is shown that the coefficient of friction between two surfaces can be changed by adding lubrication.
Show the vector addition of two forces.
Show that when the net force and net torque on a system is zero the system will be in static equilibrium, and that an object supported below its center of mass will balance.
A model crane is utilized, its design being such that the forces in its various parts may be measured. The experiment consists of the comparison of these observed and calculated forces for various loads and figurations of the crane.
The demonstration shows that when an object is supported above its center of mass, it is very stable against perturbing forces.
This demonstration shows that the sum of the torques, which can be calculated from the readings on the two scales plus the weight on the mass, is always zero when a rod is supported at both ends.
This demonstrates the capillary effect by showing that the liquid rises in each tube because the molecules of the liquid are more attached to the molecules of the tubes than they are to each other.
A block of wood is attached vertically between two strings. When the bottom string is pulled slowly, the top string breaks. When the bottom string is pulled quickly, it itself breaks.
This demonstration shows that you can magnify a force by running it over a pulley and pulling down.
This demonstration shows as the number of turns around a rod is varied, the force applied changes.
!Safety Concerns! : strobe
Take a strobed photo of a light on a car pulled by a weight on a string over a pulley. See A21.
A cart recoils after a marble is launched from it.
Conservation of momentum is thus demonstrated.
!Safety Concerns! : motor
A flexible chain circulating at high speed is shown to “walk” across the floor. Also see C30.
Balls with different coefficients of restitution are personified.
This demonstrates the principle of conservation of momentum. With a lack of external forces the total momentum of a system remains constant. Here metal bumpers are used so the carts bounce off each other elastically.
This demonstrates the principle of conservation of momentum. With a lack of external forces the total momentum of a system remains constant. Here clay is used so the two carts stick together,
6 kg carts on a 5-meter linear track can collide elastically and inelastically to provide demonstrations of collisions more dramatic than the air track. These carts can only be used in room 26-100. They are large enough to be seen easily anywhere in the room.
!Safety Concerns! : glass
Demonstrates the conservation of momentum in elastic collisions.
Demonstrates the impulse of a rebounding ball and a ball that sticks. It is shown that the ball that rebounds has a much greater impulse.
The conservation of momentum in elastic collisions is shown.
This demonstrates continuous mass transfer. One discrete collision of the small ball bearing and the large wooden plate initially does not have much effect. But many of these small collisions one after the other creates a large deflection of the plate.
Demonstrates the principle of conservation of momentum for elastic collisions. This is often referred to as a “Newton’s Cradle”
A small rectangular air table with a mobile air supply or a large 1.5m square air table can be connected to a classroom air supply. There are pucks and similar objects of varying masses that can be set in motion to demonstrate collisions in a 2D environment.
!Safety Concerns! : gun
NOTE: This demonstration has been retired and is only left here for historical record. Refer to A 15 for the updated version of this demonstration.
Demonstrates the principles of conservation of momentum and energy.
!Safety Concerns! : rocket
Conservation of momentum is demonstrated as well as Newton’s 3rd law, as the rocket ejects gas the total momentum of the system remains zero while the momentum of the rocket and gas both increase equally and opposite.
!Safety Concerns! : pressure; sound
A CO2 cylinder is mounted on the back of a tricycle. As the lecturer rides the tricycle, propellant is released from the fire extinguisher and thus the tricycle is propelled forward.
!Safety Concerns! : rocket
A rocket is mounted on an air cart. Digital timers measure the velocity of the cart and rocket. From the measurements of the weight of the rocket before and after burning, the thrust of the rocket can be determined.
!Safety Concerns! : rocket
Two air carts are accelerated toward each other with equal impulse by small rockets. Small bits of clay are mounted in front of each cart. When the carts hit, the clay absorbs the energy and the two carts stand stationary. Alternatively, two unequal-mass carts can be used.
A cut-out of the state of Massachusetts is hung from different holes on separate occasions. Each time, a ruler is used to mark a vertical line passing through the hole. The point at which these lines intersect is the center of mass[-achusetts].
A flat, irregularly-shaped piece of masonite is hung from different holes on separate occasions. Each time, a ruler is used to mark a vertical line passing through the hole. The point at which these lines intersect is the center of mass. There are three other shapes that can be used; an equilateral triangle, a sector of a circle, and a semicircle.
This demonstrates that no matter where the ruler is struck the center of mass of the ruler moves in a straight line.
Odd-shaped objects with their centers of mass marked are thrown. The centers of mass travel in a smooth parabola. The objects consist of: a squash racket, a 16’ diameter disk weighted at one point on its outer rim, and two different size balls connected with a rod.
Two people on rollerskates pull on a long rope to demonstrate the motion of the center of mass.
Two carts are connected together on the air track with a spring. The center of the spring is marked and its motion is shown while the carts oscillate back and forth.
Demonstrates the motion of the center of mass of a system. When there are no external forces on the system, the center of mass does not accelerate. In the case of the frictionless surface the only external force on the center of mass is gravity and the center of mass falls straight down. In the case with friction, friction acts as an external force and affects the center of mass.
Demonstrates the rolling motion of an object with a non uniform mass distribution.
Demonstrates the stability on an object balanced at its center of mass when the mass is distributed far from the center on either side.
A double cone and plane are placed on the bars of an inclined plane. Instead of rolling down the plane, the cone rolls up. Although the plane does slant upwards, the bars diverge, so that the axis of the cone is actually moving down.
Duplicate - See B57
A weight is attached to a cart on the air track via a string and pulley. The velocity of the cart is measured with a digital timer as the weight falls. This shows the conversion of gravitational potential to kinetic energy.
!Safety Concerns! : strobe
Demonstrates the conservation of energy by showing gravitational potential energy being converted into kinetic energy. The initial total potential energy can be calculated and compared to the final kinetic energy.
Demonstrates the conservation of energy by showing spring potential energy being converted into kinetic energy. The initial total potential energy can be calculated and compared to the final kinetic energy
!Safety Concerns! : gravity
The professor stands with his back against the wall and pulls a large pendulum up to his nose and releases it. It swings out and back almost touching his nose. This demonstrates a solid belief in the conservation of energy on the part of the professor.
!Safety Concerns! : gravity; glass
The large pendulum in 26-100 is used in conjunction with a piece of glass mounted on the sidewall. The lecturer stands in front of the glass with the pendulum touching his nose. He gives it a strong push and steps out of the way. The return swing of the pendulum breaks the glass.
Demonstrate the conservation of energy. A ball is given only potential energy initially and released from a set height, it rolls up and around a loop. The minimum height for which the ball can make the height is calculated by setting the normal force to zero and conserving energy. The ball needs both potential and kinetic energy at the top of the loop so that it can maintain circular motion.
!Safety Concerns! : motor; projectile
A pendulum swings from a support rod. A 2-meter stick is mounted horizontally to indicate the maximum height of the pendulum swing. Another rod is added to interrupt the swing of the pendulum. The pendulum is shown to reach the same height as before. The above setup can also be used as a variation on the “loop-the-loop” demonstration. The pendulum can be set swinging so that, when interrupted, its energy is just enough to make it 180° around the rod, and then fall.
This demonstration consists of a dropping ball and a pendulum released from the same height. Both balls are identical. The vertical velocity of the ball is shown to be equal to the horizontal velocity of the pendulum when they both pass through the same height.
Two spheres rigidly attached to a rotating rod will rise. This device could be used to regulate steam engines or to demonstrate the nutation of a gyroscope.
Two spheres constrained to a ring will rise when the ring is rotated.
A wooden ball is attached to the rim of a spinning wheel. The ball is held in place by a string. When the string is cut, the ball slides in a straight line upwards tangent to the wheel.
!Safety Concerns! : motor
A simple demonstration that shows the linear momentum imparted to sparks generated by contact of a steel bar with the circular motion of an abrasive wheel
A bucket of water (or filled with ping-pong balls) is spun in a circle. No water or ping-pong balls leave the bucket.
Demonstrates the relation between orbit radius and orbit velocity in circular motion.
Demonstrates the relation between orbit radius and orbit velocity in circular motion. Also see A5 (air table).
Demonstrates the conservation of energy as well as Newton's second law for rotation.
!Safety Concerns! : motor
Demonstrates the acceleration of uniformly rotating objects.
Duplicate - see X10
A brass block is supported by a rubber band and a pin bearing. The block can be placed in various orientations and spun by winding the rubber band. When in a symmetric orientation the block wobbles very little, but when in an asymmetric orientation the block feels a torque and wobbles greatly.
!Safety Concerns! : strobe
A repeating strobe lamp is adjusted to measure the frequency of a rotating disk. A black disk with white numbers can be seen to stand still.
Tensioned fabric with a large mass in the center and marbles provides an analogy for trajectories in a central potential.
Demonstrates the effect moment of inertia has on rolling motion. Also demonstrates that uniformly dense objects of the same shape roll at the same rate down hill.
Demonstrates the conservation of angular momentum.
A weight is attached to a string wrapped around the rim of a wheel. The weight falls and spins the wheel. The wheel's moment of inertia is calculated by modeling it as a disk. The calculated and measured time for the mass to fall can then be compared.
This demonstrates the effect moment of inertia has on acceleration. The moment of inertia of the system can be increased or decreased and angular acceleration can be seen to decrease or increase respectively.
A cylinder weighted off-center seems to defy gravity by remaining stationary on an inclined plane.
!Safety Concerns! : projectile
Demonstrates the effect short duration forces have on systems. In order to accelerate a mass (i.e. make it move) a force has to act for an appropriate amount of time.
!Safety Concerns! : glass
Demonstrates the effect short duration forces have on systems. In order to accelerate a mass (i.e. make it move) a force has to act for an appropriate amount of time.
!Safety Concerns! : fire
This demonstration illustrates the earliest form of steam engine, as described by Hero of Alexandria, about 150 B.C. It consists of a spherical container with two reaction jets and a bearing on which the bulb can rotate.
Demonstrates the principle of conservation of angular momentum.
A model train track is mounted on a horizontal bicycle wheel which is free to rotate. The train is put on the track and started. Many different initial conditions are possible to demonstrate conservation of angular momentum.
!Safety Concerns! : pressure
A metal sphere has a small mass on a radial rod and rests on an air bearing. The gyroscope can be used to show uniform procession, torque-free precession, and nutation. This is described rather completely in pages 328-333 of Kleppner/Koldenkow
An air-supported ball has a long rod through its diameter. This acts as a gyroscope without toque. The plan of rotation of the rod can be tilted by lightly hitting the rod. The system can be made to precess by attaching weight to an end of the rod.
Demonstrates gyroscopic precession due to gravitational torque.
!Safety Concerns! : motor
A similar demonstration as B137 is performed by a spinning bicycle wheel having a universal bearing at one end of its axle and resting on a vertical support.
!Safety Concerns! : motor
This gyroscope, powered by line voltage, maintains a constant angular velocity for extended periods of time.
!Safety Concerns! : motor
This gyroscope has three degrees of freedom and is large in size. It maintains a relatively constant velocity by means of an induction motor. It is very convenient for a general discussion of gyroscopes.
!Safety Concerns! : motor
A gyroscope inside a suitcase is spun up via a connection to the outside of the suitcase. The suitcase is carried across the lecture hall. When the lecturer turns while walking , the gyroscope causes the suitcase to rise about the handle.
Shows an application of a gyroscope with two degrees of freedom. It is shown via the video projection system.
Demonstrates gyroscopic precession due to gravitational torque.
A gyroscope and a balancing cross bar are mounted on two wheels. This device is placed on a wire stretched across the length of all three lecture tables. It then keeps its balance and rolls along the wire without falling.
Numerous other small gyroscopes are available. These can be shown to the class by use of the video projection system.
An example of precession without a gyroscope.
A sand-carrying cart on a track leaves a trail of sand when it travels over a rotating table. This shows the effect of the coriolis force.
!Safety Concerns! : shoddy construction
A long plank is mounted on a rotating platform. Two people sit on either end of the plank and toss a ball back and forth, demonstrating the Coriolis Effect.
In this demonstration, it is possible to find the approximate length and diameter of an oleic acid molecule, an unsaturated, naturally occurring fatty acid.
A cart connected by springs to both ends of an air track demonstrates simple harmonic motion.
An adjustable mass hanging from a spring demonstrates simple harmonic motion.
!Safety Concerns! : motor
The motion of a motor-driven ball rotating in a circle is shadow-projected sideways. It is shown to coincide with the motion of a mass on a spring executing simple harmonic motion at the same frequency.
!Safety Concerns! : fluid
A can of spray paint is attached to a spring oscillator. A sheet of paper toweling is run past the oscillating can. The result is a sine wave on the paper. Demonstrates the sinusoidal nature of simple harmonic motion.
Various size balls and lengths on a string can be shown or timed.
!Safety Concerns! : gravity
Demonstrates the prince of conservation of energy. NOTE: This demonstration has been retired as we no longer use the 26-100 space. Something similar could be set up on a smaller scale in 6-120 upon request.
An irregularly-shaped object exhibits harmonic motion.
An iron ball swings at the end of a rigid rod.
A mass on a spring, a simple pendulum, a rod, a hoop, and a solid disk are suspended from the same support. They all oscillate with the same frequency.
Two identical pendulums are released at the same time from different heights. For small amplitudes, the pendulums remain in phase for about ten periods of oscillation
Demonstrates the difference in motion between a damped and undamped system. The daped system will have the same frequency but with decreasing amplitude over time.
Demonstrates harmonic motion of an object as well as conservation of energy.
This visually demonstrates the interplay of potential energy to kinetic energy by observing the speed of the ball at different points on the track.
!Safety Concerns! : glass
Demonstrates an example of harmonic motion. However, this is really a demonstration of the difference between adiabatic and isothermal measurements of specific heat.
!Safety Concerns! : fluid
A u-shaped clear plastic tube filled with fluorescent-dyed water is used to demonstrate harmonic motion
A torsional Balance has a constant-torque spring and adjustable weights on its cross bar. This can be shown on the video projection system.
Duplicate - see C11
Two identical pendulums are coupled by means of a light rod loosely connected to the pendulums’ strings
Two identical rigid pendulums are coupled by means of a light spring. Three springs with different spring constants are available.
Error - empty line in description
Five carts coupled together with six matched springs are mounted between a fixed end and a variable motor-driven end on a 2.5 m air track. By adjusting the speed of the motor, five different modes of vibration can be attained. This demonstration can also be done with three carts on a 1.5 m air track.
A hacksaw blade has a weight attached to each end. The center of the blade is tightly held in vise. The two halves of the blade then behave like coupled oscillators
The pendulum consists of a 30 mm wide helical spring, made of 1 mm thick steel wire and having 140 to 150 turns. One one end of the spring, a heavy iron cylinder is attached coaxially with the helix and provided with four mutually perpendicular radial pins. Each of them carries a flat, metal disc, which can be brought closer to the cylinder axis or farther away from it by means of threads cut into the disc and the pin. In this way, the moment of inertia of the iron cylinder is variable within wide limits.
!Safety Concerns! : laser
An approximately erratically damped ballistic galvanometer is used to show the effect of magnetic damping on the harmonic motion of a reflected helium-neon laser beam.
A baseball bat is hung vertically from a rod. The effect of striking a baseball bat at its center of percussion is demonstrated.
The effect of striking a baseball at its center of percussion is demonstrated. A pencil located at the axis of rotation of the bat breaks when the bat falls on a block at a point other than its center of percussion.
A wooden rod is placed between two ping-pong balls. When the rod is struck above or below the center of percussion, the balls move. When struck at the center of percussion, neither ball moves.
A frame carries five wire forms bent in helices and capable of being turned about their axes. When projected on the screen, they appear as waves of sinusoidal form that progress as the wire shapes are turned. A mask can be used to expose the display of the sine waves one after the other.
A small spring is connected vertically to a mechanical oscillator driven by a sine wave generator. Different longitudinal resonant frequencies can be observed. Projection TV is used.
Wave motion phenomena including propagation, reflection, interference and a number of resonant modes can be shown.
Rods ranging in size from 10 cm to 40 cm are attached to a steel rod that flexes to produce wave motion down its length. The machine can show standing waves, reflection, damping, resonance, impedance matching, reflection at the boundary between two media, and superposition. The end of the rods are painted to make the wave motion visible when illuminated with UV light. This machine can also be motor driven.
A 20-ft-long torsion pendulum is suspended from the ceiling of room 26-100. It can be used to display travelling and standing waves as well as critically damped waves.
A three foot apparatus shows phase and group velocity for two different frequency components and a superposition of the two. The waves are painted with fluorescent paint on rods that move vertically, and are quite visible when illuminated with UV light.
!Safety Concerns! : motor
A long beaded chain is looped over a motor pulley. the motor is gradually brought up to full speed. A pulse is seen to travel slowly down to the bottom of the chain. A quick blow to make the chain come off the motor pulley results in the chain maintaining its shape for some time.
!Safety Concerns! : strobe
Various wave patterns can be demonstrated.
A synthesizer is available to demonstrate addition of sine waves and fourier decomposition.
A stretched spring shows transverse wave motion and the motion of pulses. A slinky shows longitudinal waves.
Longitudinal waves are set up in Magnesium and Aluminum rods by striking the ends with a hammer. Wiping the rods gently with one's finger, outward from the center, removes any transverse wave. Touching the ends removes the longitudinal wave.
A long spring, clamped or held by a student at one end, is hand-driven by the demonstrator at its other end. The higher the driving frequency achieved, the more nodes are observed along the spring.
A transverse motion generating machine creates vibrations in a stretched length of surgical tubing. A strobe light allows nodal patterns to be more easily seen.
!Safety Concerns! : strobe
An Oscillator signal is used to excite vibrational modes in a thin circular rubber membrane. The modes can be viewed with a strobe light.
A thin metal sheet, fixed in the center, is excited in vibrational modes with a large loudspeaker. Fine sand sprinkled on the plate shows various modes of vibration in a plane.
Three thin metal sheets of different shapes are stroked with a cello bow. A thin layer of sand on the surface rearranges itself to delineate nodes and antinodes.
A soap film on a ring is driven by a loudspeaker. The film is viewed by reflecting light off the surface of the film and projecting it on screen.
The signals from two separate oscillators of different frequencies are mixed and their resultant is displayed on an oscilloscope.
Open and closed organ pipes, ranging in size from 10 cm to 1 m, are available
A large British warning horn, a duck coil, and a small siren whistle provide amusing sound effects.
A large number of tuning forks with or without resonator boxes are available to choose from.
The sound of a tuning fork is picked up, amplified and displayed on an oscilloscope
Two identical tuning forks are placed on the table with their resonator boxes facing each other. If one of the forks is struck, the other will start to resonate at the same frequency.
The demonstrator can exhibit their musical talent.
!Safety Concerns! : asphyxiation
Helium introduced into a resonant cavity, including the lungs of the demonstrator, will increase the frequency of all pitches originating in the cavity
Signals from two audio generators are mixed and the result is heard with a loudspeaker.
Tone bursts are produced , displayed on an oscilloscope and heard with a loudspeaker. By varying the pulse width, one can measure the point where the burst starts to have a tonal quality.
Duplicate - see P3
!Safety Concerns! : glass
A speaker connected to an audio oscillator is placed at one end of a plexiglass tube. The oscillator is tuned to the resonant frequency of the glass tube. A microphone connected to an oscilloscope is drawn down the length of the tube. Standing waves in the tube and the distance between them are recorded on the scope.
Two speakers, mounted on the lecture table and facing each other, are driven by an audio generator. A microphone is introduced between the speakers and the sound waves are displayed on an oscilloscope.
A speaker and microphone are mounted on a lens bench facing one another. A phase measurement between the speaker and microphone signals is made on an oscilloscope. The distance required to traverse through a 360 degree phase shift is noted. Knowing the frequency and distance, the speed of sound is computed.
A speaker is placed at one end of a 5 meter long tube which can be filled with Helium. A microphone is placed inside the tube. The delay between the input signal and the microphone signal is measured once with the microphone halfway in the tube, and once with the microphone at the end of the tube opposite the speaker. From these measurements, the speed of sound can be calculated.
A 4000 Hz tuning fork is stricken and moved quickly by hand in a back-and-forth motion perpendicular to the rows of seats in the audience. The students sitting in front of the path of the tuning fork will best notice the Doppler shift effect. The tuning fork is then oscillated parallel to the rows of seats. This time the audience will not hear the Doppler shift.
The length of corrugated rubber tubing is swung by hand, and a frequency modulation can be heard in the plane of rotation.
A cart is connected by a spring to one fixed end of the air track and by another matched spring to a variable-speed driving motor. The resonant frequency of the cart-springs system is then found.
!Safety Concerns! : motor
A mass on a spring is driven by a large geared motor apparatus and exhibits resonance at the appropriate frequency. By attaching a horizontal disk above the mass, one can also damp the system.
!Safety Concerns! : motor
A torsional balance is driven by a motor. Arrows that can be shadow-projected display the driving and the oscillating frequency. Resonance can be readily demonstrated.
A wood block is attached to the center of a long rubber hose. The demonstrator and a volunteer hold the ends of the hose, and one of them swings the hose up and down until the resonant frequency is reached and the block oscillates with maximum amplitude.
!Safety Concerns! : glass
A thin, long glass tube is mounted vertically with an opening at the bottom from which an ink-water mixture can be added. A small speaker excites resonant modes in the air column above the ink water column. Resonant points can be heard, and the corresponding level of the liquid marked on the glass
!Safety Concerns! : glass
A microphone is placed inside a large flask tightly sealed with a cork. The air resonance of the flask is observed on an oscilloscope when the cork pops out of the mouth. This demonstration can also be done with an air gun blowing across the mouth of the flask
!Safety Concerns! : glass
A large box or the large flask can be used to demonstrate resonant cavities. A microphone is placed into the cavity while a speaker is directed at the mouth. A function generator is used to sweep the frequency from below the fundamental to about 10X that. This is displayed on an oscilloscope. Resonance occurs at various normal modes of the box or flask.
!Safety Concerns! : fire
A very large pipe can be made to resonate by heating a copper screen installed approximately one quarter way up the length of the tube.
!Safety Concerns! : glass; sound
Sound is used to shatter a wine glass.
A small spring is connected vertically to a mechanical oscillator driven by a sine wave generator. Different longitudinal resonant frequencies can be observed. Projection TV is used.
This set-up consists of a 60 cm rod fitted with a stem for mounting the apparatus on a standard rotator. One end of the rod holds a reed; the other has an attached counterweight. The reed is rotated until it emits an easily recognizable musical rone. The students can observe that the pitch seems to rise as the reed approaches, and seems to lower as the reed goes away, even though the speed of rotation is constant.
A simple chaotic system.
The pivot position of a physical pendulum is varied and its period is recorded. The period of the pendulum will be minimized at a certain position. This position is equal to a constant that includes the pendulum's moment of inertia. Thus, one can find the pendulum's moment of inertia.
!Safety Concerns! : fire
Standing pressure waves in propane lead to a visible wave of flame heights.
To show the “creation” of charge using the triboelectric effect; and, to show the repulsion of like charges and existence of two types of charge.
Demonstrate induced charge on a conductor as well as show the “1/r^2” property of Coulomb’s Force Law.
Demonstrates induced charge on a conductor as well as shows the “1 over r squared” property of Coulomb’s Force Law.
Show operation of an electroscope with charged rods.
To show repulsion between two pith balls given like charges.
Show that charge can be removed from a rug by rubbing your feet on it.
Show that particles of like charge repel each other.
Show that an isolated object receives a buildup of charge and that like charges repel.
Show the separation of two pith balls, both with a like charge.
!Safety Concerns! : HV
Shows the repulsion between two plates that have the same charge.
Demonstrate buildup of static charge when a person is rubbed by fur.
Show operation of an electroscope by induction only.
Explain operation of the electrophorus.
!Safety Concerns! : charge
Demonstrate the generation of high voltages with the Wimshurst Machine (see E1).
!Safety Concerns! : charge
Demonstrate the charging of objects by using induction.
!Safety Concerns! : charge
Show the varying electric field lines of different conductor arrangements.
!Safety Concerns! : charge
Show the electric field lines of a Van De Graaff Generator.
!Safety Concerns! : charge
Demonstrate the electric field lines between parallel-plates, as well as show electrostatic induction. See E3 for fringe fields.
!Safety Concerns! : charge
Show the electric field lines between metal conductors as well as electrostatic induction.
!Safety Concerns! : charge
Demonstrate electric field lines between two charged spheres.
!Safety Concerns! : charge
Show the electric field lines of a sphere and an infinite plane.
!Safety Concerns! : charge
Show that a dipole will line itself up with the electric field line.
!Safety Concerns! : charge
[DEMONSTRATION UNAVAILABLE] A small dipole on a rotating stand is placed between the plates of a capacitor. This demonstrates that the moment of an electric dipole will seek to align itself with the electric field.
!Safety Concerns! : charge
A fluorescent tube swings at the end of a long plexiglass rod. It is made to rotate and then brought near the VdG generator. The tube lights up when pointing radially away from the VdG. The same can be done with a small neon tube. Also, the tubes can be hand-held and made to flash by grounding.
!Safety Concerns! : charge
A bucket on an insulated stand is placed in the field of a VdG generator. Electric charge is scooped up from the side of the bucket closest to the VdG and transferred to an electroscope. Next, charge is taken from the opposite side of the bucket and transferred to the same electroscope. The electroscope discharges, showing the opposite signs of the induced charges on each side of the bucket.
!Safety Concerns! : charge
A conducting gallon paint can with an orifice in the top is charged with the Wimshurst Machine. The lecturer attempts to charge two small conducting spheres by induction inside the container. Because of the absence of an electric field inside the container, the spheres get no charge. If the same process is repeated outside the container, the spheres become charged oppositely. This is shown with an electroscope. This demonstration can also be done with a hollow sphere.
!Safety Concerns! : charge
A conducting gallon paint can with an orifice in the top is charged with the Wimshurst Machine. Using a charge scoop, show that touching the inside of the conductor produces no charge but touching the outside will. This is shown with an electroscope. This demonstration can also be done with a hollow sphere.
A tear drop shaped conductor on an insulating stand is charged. Charge is scooped up from various points on the surface of the conductor with a proof plane and transferred to an electroscope. It is demonstrated that the charge density is greater at the areas of greater curvature. This demonstration can also be done with a bucket.
!Safety Concerns! : charge; arc
Different sized spheres at the end of a grounded rod are brought separately in the vicinity of a VdG generator. Breakdown of the air occurs and "lightning" sparks are created between the VdG and the spheres. Smaller spheres result in smaller sparks. A sharp point at the end of the discharge rod produces a Corona discharge (St. Elmo's fire). A shadow-projected electroscope placed nearby shows that discharge is actually taking place.
Demonstrates the conducting properties of ionized air.
A conducting pinwheel is made of a horizontal pivoting rod with sharp bent ends. When placed on top of a VdG generator, the corona discharge creates ions in the air surrounding the points. Due to the same polarity of these ions and the points, the latter are repelled and the pinwheel rotates.
!Safety Concerns! : charge
Demonstrates that there is no electric field inside a conductor placed in an external electric field. See D33 for the small TEAL version.
!Safety Concerns! : charge
Tinsel or an uncharged electroscope placed inside an insulated cylindrical wire mesh cage is shielded from the field of a VdG generator. This demonstration is especially suitable for smaller classrooms. This is the small version of D32.
!Safety Concerns! : HV
Demonstrates how a Van De Graaf Generator is able to achieve a high potential.
!Safety Concerns! : water
The electrostatic generator consists of water falling from two spigots through two metal cylinders and into two cans that are cross-connected to the cylinders. It is capable of generating about 10kV before discharging across a spark gap. The electrodes and sparks are very visibly TV-projected on the video screen.
!Safety Concerns! : explosion
Gas explosion by spark.
!Safety Concerns! : fire
A rectangular transparent container is filled with smoke and illuminated so as to make the smoke visible. A high voltage terminal in the container is connected to the Wimshurst machine. When the Wimshurst is cranked, the smoke swirls and quickly dissipates.
A board displaying an eclectic collection of capacitor types.
!Safety Concerns! : charge
Demonstrate that a capacitor can store large amounts of charge (see D14).
!Safety Concerns! : charge
This three-piece capacitor consists of two metal cups separated by a glass cup. When assembled it can be charged with the Wimshurst machine. When disassembled the metal cups can be brought into contact with each other and no spark will be generated. When the jar is reassembled, it can then be discharged. A visible and audible spark is produced showing that the charge resides on the glass dielectric.
!Safety Concerns! : charge
A Parallel plate capacitor is connected to the Wimshurst machine. A conducting ping-pong ball hangs on a 1m string on the outside of one of the plates. As the Wimshurst is charged the ball will follow the fringing electric field lines. The ball can also be placed in between the plates and will bounce back and forth between the plates as the Wimshurst is charged (see D18).
!Safety Concerns! : HV
A parallel plate capacitor is charged to 1KV. The Braun electroscope is across the plates to detect the potential difference. The relation between charge, potential and capacitance can be demonstrated.
!Safety Concerns! : HV
Various dielectrics are placed between the charged plates of the parallel-plate capacitor. Changes in the deflection of an electroscope can be observed when inserting or removing a dielectric or varying the distance between the plates.
!Safety Concerns! : HV; explosion; sound
A 100 μF oil-filled capacitor is charged to 4 KV. This takes approximately 15 to 20 minutes. The capacitor is discharged through a 12 inch length of iron wire. The wire explodes with a loud bang and a showering of sparks. A plexiglass shield is used to prevent the sparks from reaching the audience. This demonstrates the large amounts of power capacitors can produce. The energy stored is about 800J which gets discharged in microseconds.
!Safety Concerns! : MHV
A DC power supply is used to charge a bank of twelve 80 μF capacitors totaling 960 μF. The capacitor bank is charged to three different values. 80 VDC, 120 VDC and 200 VDC and discharged each time through a 75 W bulb. Caution - the bulb will burn out at 300 VDC.
Demonstrates the effect resistance and capacitance have on the RC time constant of an RC circuit.
A 12V battery is used to charge a 10,000 μF electrolytic capacitor through a 1K ohm resistor. Voltage and current are displayed using an overhead projector.
!Safety Concerns! : MHV
A 100 VDC Power supply is used to charge a bank of twelve 80 μF capacitors totaling 960 μF. The capacitor bank is charged and discharged through a 6W lamp indicating both the charge and discharge time.
This is a variable resistor and capacitor across a speaker in series with an audio source. It demonstrates the principle of a low or high pass RC filter.
!Safety Concerns! : MHV
Demonstrates an oscillator using RC time constants. See explanation in E13.
!Safety Concerns! : HV
Demonstrates an oscillator using RC time constants.
!Safety Concerns! : strobe
This demonstrates the use of capacitors in commercial products. A repeating electronic strobe or camera flash is used.
Duplicate - see B111
!Safety Concerns! : fluid
A mixture of cornstarch and vegetable oil drips in a constant stream from a funnel. A charged rod is brought close to the stream and the dripping stops.
A wide selection of 1st and 2nd order passive filters can be constructed and switched between.
!Safety Concerns! : fire; mains
Demonstrates that free ions are needed to conduct current. When glass is at room temperature, it acts as an insulator. However, when glass is sufficiently heated by a torch, it becomes an ionic conductor. Ionic bonds in the glass are broken, allowing the charge carrying ions to move freely. Thus, when the glass is melted the current can flow, which closes the circuit and lights the bulb.
!Safety Concerns! : mains
A hot dog is placed between two metal terminals which are connected to a 110V AC switch. When the switch is thrown the hot dog “cooks.” This demonstrates the conversion of electrical energy to heat.
!Safety Concerns! : mains
A car battery is shorted very quickly with a large wrench. This demonstrates how high the short circuit current can be on an auto battery.
!Safety Concerns! : cryogen
Demonstrates the effect that temperature has on the resistance of a conductor. A 6 V lamp is connected in series with a coil of very fine copper wire and a DC power supply. The voltage is adjusted so that the lamp glows dimly. When the coil is immersed in liquid nitrogen the resistance of the wire decreases causing the current to increase and the lamp to glow brightly.
!Safety Concerns! : mains
Demonstrates that pure water on its own does not conduct current. It must have charge carrying ions in order to do so. Salt is added to deionised water and lights a light bulb.
!Safety Concerns! : acid; fire
The basic principle of a battery is demonstrated. The internal resistance of a battery is also measured and demonstrated.
!Safety Concerns! : acid; fire
Demonstrates the basic principles of an acid battery.
!Safety Concerns! : HV; lead; fluid
Demonstrates the process of using electrodeposition to coat an object in a layer of metal.
Demonstrates the relation between voltage and current as well as how voltages add in series.
Demonstrates the relationship between length of wire and resistance. As the length of a wire is increased, the resistance of the system increases.
Demonstrates relationship between voltage and current in both series and parallel circuits.
Demonstrates that resistors in series add linearly.
!Safety Concerns! : MHV
Demonstrates Kirchhoff's loop rule by showing that the total voltage drop across an entire circuit is zero. The voltage drop of each item in the circuit is shown to add to the same voltage as the input voltage.
Demonstrates the use of a wheatstone bridge to determine an unknown resistance.
Demonstrates the non-linearity and initial high current flow of a light bulb.
!Safety Concerns! : mains
The voltage and current relationship of a resistor, a Zener diode, a capacitor or a light bulb is displayed on an oscilloscope.
A sawtooth waveform is the input for the Y axis of an oscilloscope. It is also the input for a lamp or a 51 ohm resistor which is connected to the X axis. The light bulb shows a non-linear change as the temperature of the bulb varies. This is compared to the resistor which shows a linear change. [CURRENTLY UNAVAILABLE]
Electrodes are placed on a human subject and the heartbeat is monitored with an oscilloscope. It is shown that muscle contractions produce electric signals which are shown on the video screen.
A board with two 75W light bulbs on it has a switch which allows the two bulbs to be set into ‘parallel’ or ‘series’ wiring configurations. When the bulbs are in parallel, they are both bright, while in series, they both appear dim.
A large bar magnet compass is deflected by hand with a magnet.
A bar magnet is placed between two transparent sheets of plastic and put on a document camera or projector. Iron filings are sprinkled on the top. A broken magnet can also be used to show that there are no monopoles.
A few small demos to show magnetic attraction of seeming ‘non-magnets’ to a permanent magnet.
Two or more 1-inch disk-shaped magnets will levitate over each other.
!Safety Concerns! : HV
A small cathode ray tube is used to show an electron beam. The beam can be deflected using a bar magnet. Also see V9.
A large magnet is brought close to a CRT TV. The image will become distorted in the magnetic field.
!Safety Concerns! : cryogen
Demonstrates the principle of superconductivity using a superconductor and liquid nitrogen.
!Safety Concerns! : car battery
Demonstrates the Lorentz force on a current carrying wire.
!Safety Concerns! : car battery; heat
Demonstrates the Lorentz force as well as Biot–Savart law for current carrying wires. Also, shows the difference in the direction of the force based on the direction of the current.
!Safety Concerns! : mains
Demonstrates torque on a magnetic dipole in an external, constant magnetic field. This is the principle upon which galvanometers work.
!Safety Concerns! : laser
This is a sensitive balance used to measure an electric current that passes through two horizontal bars connected in series. The lower bar is fixed and the upper is balanced a few millimeters above it. Because the current passes in opposite directions through the two bars, the bars will repel each other an amount dependent upon the amount of current run through the two wires. Analytical weights are placed in a small pan on the upper bar to displace it downward. The current is then increased until the bar returns to its equilibrium position. The deflection of the balance can be shown by means of a laser beam reflected off a mirror onto a distant screen.
!Safety Concerns! : car battery
Demonstrates how currents generate magnetic fields using the right hand rule. Various types of current carrying configurations can be shown. The G12 plate is equivalent to the inside of a single turn coil.
!Safety Concerns! : car battery
Magnetic Fields - FIeld Lines of a Wire
!Safety Concerns! : car battery
Demonstrates the field lines around a vertical current carrying wire using multiple sensitive compasses.
!Safety Concerns! : car battery
Demonstrates the field lines around a horizontal current carrying wire using multiple sensitive compasses.
!Safety Concerns! : car battery
Demonstrates how currents generate magnetic fields using the right hand rule. Various types of current carrying configurations can be shown. Here, an eight turn solenoid set into a plexiglass plate has iron filings sprinkled on it, showing the magnetic field induced by the current running through the solenoid.
!Safety Concerns! : mains
A 0.6 meter diameter coil is connected to 125 VDC at 5 amps. The "B" field is measured using a Gaussmeter. One-half of a Helmholtz coil is used.
!Safety Concerns! : mains
Demonstrates that the magnetic field of a solenoid is constant within the solenoid and then starts to change near the edges.
!Safety Concerns! : mains
Demonstrates the magnetic field of a helmholtz configuration. Shows that the two fields of the coils add and produce a uniform field in the middle.
!Safety Concerns! : mains
Demonstrates the magnetic and electric fields of a long solenoid. Shows that the field is constant within the solenoid, and starts to change near the edges.
!Safety Concerns! : mains
A slinky is stretched out on a wooden rod and connected to 110 VAC. When power is applied, the slinky immediately collapses.
This demonstration measures the potential difference across a conductor carrying a current when that conductor is placed in a magnetic field. Three meters are used to show the values.
Tags: 8.02, magnetic fields
A sensitive center zero projection meter is connected in series with a long cable. When the wire is introduced to the field of a magnetron magnet, the meter will deflect showing an induced current. When the cable is removed from the field the meter will deflect in the opposite direction.
A single-turn copper coil is connected to the Keithley Electrometer. When the coil is moved through the magnetic field of a magnetron magnet the electrometer will deflect, giving a reading of approximately 3mV.
A 9" coil with 120 turns is connected to an ammeter. A bar magnet is passed through the center of the coil, inducing a current which is shown on the meter. Reversing the poles or direction of the magnet will reverse the current. Passing the magnet through at different speeds will show different currents.
A coil with many turns (number of turns unknown) is connected in series to a small light bulb. When the coil is passed between the poles of a magnet the light bulb glows. It is possible to burn out the light bulb.
!Safety Concerns! : mains
A 30 H magnet with poles of about 10 cm. square, is connected to a 12V storage battery. After power is applied an aluminum ring is dropped into the field of the magnet. The ring falls slowly when entering or leaving the field and fast when totally inside the poles. This demonstration illustrates Faraday's and Lenz's Law. This demo is also shown with a smaller electromagnet, connected to 125VDC.
A 42-turn coil with a diameter of 57 cm. is free to rotate about its axis. When rotated by hand, a current is produced in the coil due to the earth's field. This is not a very clean signal and the orientation of the coil does not seem to matter.
An old generator with a permanent magnetic field will light a small light bulb (or several) when turned with a hand crank. Lighting several bulbs at once will take more effort. It can also be run as a DC motor when connected to a 12 V storage battery.
A four-turn flexible coil is placed around a long solenoid. The solenoid is connected to 125 VDC at 5A. When the switch is closed a current is induced in the coil. The current is displayed on a center-zero projection meter. The switch is opened and the current shown is equal and opposite. The coil can be deformed around the solenoid and the readings will remain the same. The wire loops are then doubled around the solenoid and the demonstration is repeated. The eight-turn coil now yields twice the current.
!Safety Concerns! : HV
A long length of wire, connected to an AC voltmeter, is looped around a solenoid acting as the primary of a transformer. As the number of turns are increased the voltage increases linearly.
!Safety Concerns! : HV; heat
A single-turn coil of 3/4" copper has a nail secured to it to complete the winding. When placed over a high turn solenoid, and power applied the nail glows brightly. This demonstration shows the principle of a welding transformer or an induction oven.
!Safety Concerns! : HV; arc
A 10,000 turn coil with a spark gap is used as the secondary of a transformer. The spark gap resembles a rabbit ears antenna, with the gap larger at the top than the bottom. When 110 VAC is applied to the primary an arc will move from the bottom of the gap to the top. This is due to convection and will not work upside-down.
!Safety Concerns! : car battery; HV
A high-voltage induction coil is connected to a 12 volt storage battery. When power is applied VERY HIGH VOLTAGES are developed across a variable spark gap. The marconi coil is an historic device from c. 1901-1906. Believed to be of the same model as the marconi coil aboard the
!Safety Concerns! : mains
Two pendula made of copper plates can be mounted between the poles of an electromagnet. One pendulum is solid while the other is slotted. First the solid pendulum is set in motion and the magnet is switched on. The motion will damp out very quickly. The solid pendulum is then replaced with the slotted one. The demonstration is repeated and the slotted pendulum continues to oscillate.
!Safety Concerns! : mains
A large aluminum plate is moved between the poles of an electromagnet. Due to eddy currents the force needed to move the plate is sizable. This is a good demonstration to have a student perform.
!Safety Concerns! : mains
A coil of copper wire with flexible leads is placed on a large 1" thick aluminum plate. The coil is connected to a 110 VAC variac. When power is applied eddy currents are generated in the plate and the coil levitates.
One aluminum tube and one plexiglas tube are mounted on a vertical stand. Two apparently identical bobs are dropped through the tubes at the same time. Because one bob is magnetic and one is not, the rate at which the bobs fall will depend upon which bob is dropped through which tube, i.e. the magnetic bob will fall slower in the aluminum tubes, but all other configurations should display no variance in fall time.
!Safety Concerns! : power; mains; arc
A large 12 H solenoid is connected to 125 VDC through a knife switch with a long insulated handle. The switch is quickly thrown open and a very bright arc 10" long is seen.
Two 120-turn coils are placed facing each other on the lecture table. One coil is in series with a switch and a dry cell battery. The other coil is connected to a sensitive center-zero galvanometer. When the switch is closed or opened, a current is induced in the second coil and a meter deflection is noted.
Two 120-turn coils are placed facing each other on the lecture table. One coil is connected to the generator and the other is connected to an oscilloscope. The oscilloscope will display the sine wave induced from the coil connected to the generator.
!Safety Concerns! : car battery
A 30 H coil with an internal resistance of 4.5 ohms is connected to a 12 V storage battery. Two light bulbs are connected to the coil; one in series to monitor the current and one in parallel to monitor the voltage. When a 4.5 ohm resistor is connected instead of the inductor coil and the switch is thrown, both bulbs light simultaneously. When the inductor is introduced to the circuit instead and the switch is thrown, the voltage bulb lights immediately while the current bulb lights slowly over a 7 second time period.
A large solenoid and a decade resistor are connected in series to a square wave generator. The voltage across the inductor and the voltage across the resistor are shown on an oscilloscope. The display shows the RL time constant.
!Safety Concerns! : mains; MHV; projectile; cryogen
An iron core solenoid is connected to a 110 VAC variac. An aluminum ring is placed over the iron core of the solenoid. The voltage can be adjusted on the variac to make the ring levitate. The voltage can also be preset at a high level, so that when power is applied, the ring will shoot up toward the ceiling of the lecture hall. The ring can be immersed in liquid nitrogen and the demonstration repeated. The ring will be propelled a much greater distance. A second ring with a cut in its radius will not levitate. DC power can also be used. The ring will jump about 5 cm and return.
A sine wave is input to a series circuit consisting of a decade inductor and a decade resistor. The voltage across the resistor and the inductor is observed on an oscilloscope. The phase shift can be changed by adjusting the variable components. This demonstration can also be shown using the large 1 H solenoid.
A decade inductor and a resistor are connected in series to the output of a radio. The LR circuit acts as a low pass filter.
!Safety Concerns! : mains; arc
A 42-turn coil with a diameter of 57 cm is free to rotate and is connected through a DPDT reversing knife switch to 125 VDC. A very strong magnet is mounted outside the rim of the coil. The switch is quickly thrown from one pole to the other. As the coil passes through the magnetic field it is repelled and rotates. Switching at the correct speed will cause the coil to act as a DC Motor.
!Safety Concerns! : mains
A coffee can mounted on needle bearings is placed under a coil. A second coil is placed perpendicular to the first coil. Both coils are connected to the same variac. The phase difference between the fields of the two coils causes the can to rotate, thus creating a simple induction motor.
!Safety Concerns! : HV
A toroid with three different windings is connected to 220 VAC 3 phase. A simple induction motor is first demonstrated by placing an aluminum egg in the rotating magnetic field created by the 3 phase currents. The same procedure is used for a metal ring. By using a strobe, the speed of rotation of the ring can be determined. A ring with a cut through its radius is unable to rotate. A board can be placed over the rotating magnetic field and small magnets placed on the board. It can then be seen that the field is changing since the magnets jump up and down on the board.
!Safety Concerns! : motor
A magnet with a very strong magnetic field is held in place on an aluminum disk. The disk is attached to a variable speed motor. When the disk rotates the magnet will levitate above it due to eddy currents generated in the disk.
Three solenoids with 20, 40 and 80 turns are connected to a milliammeter mounted on a transparent base. A magnet is inserted in each coil producing an electric current measured with the meter.
Two resistors with a ratio of 9:1 are connected in series in the shape of a circle. The resistors are 180 degrees apart. The resistors are placed over a coil which, when energized, induces a current in the circuit. The voltage drop across each resistor is shown on a DMM and has a ratio of 9:1 with opposite polarity. This shows that the electric potential between two points depends on the "routing" of the current.
Two 120-turn coils are placed facing each other on the lecture table. One coil is connected to a radio or other audio source and the other is connected to a speaker. The speaker will play audio from the radio when the coils are aligned.
The Professor gets to rock out with a semi in tune Neely original electric guitar.
A rod is propelled by the lorentz force along two rails in a magnetic field.
Error - empty line in description
!Safety Concerns! : fire
The Sterling engine, patented by Robert Sterling, is a complex system that utilizes the regeneration process to transfer thermal energy to mechanical work. The engine consists of cylinders and pistons, and a flywheel assembly. The four cycle engine can be made to operate by applying heat to the bottom cylinder with a blow torch. Heating causes the air in the cylinder to expand, thus moving the piston upward. Heating takes about 5 to 7 minutes before the engine starts to turn.
!Safety Concerns! : fire; projectile
A mounted copper tube (24” long and 1” diameter) dilled with 5 ml of water is tightly sealed with a cork. The system is pressurized by heating the tube with a blow torch. After a few minutes of heating, the cork “pops” out at an impressive distance of 4 to 5 meters.
!Safety Concerns! : fire
A brass ball and ring are individually connected to a rod and wooden handle. Thwne the brass ball and ring are at room temperature, the ball will easily pass through the ring. When the ball is heated using a blow torch, the ball expands and it will not pass through the ring. This shows the concept of thermal expansion.
!Safety Concerns! : fire
A brass rod (14” long and ¼” diameter) is mounted horizontally on a board. The rod is fixed at one end while the other is free to move against a pointer indicator. The flame of a blow torch is moved at a steady rate along the rod from one end to the other, and the change of the pointer indicator is noted.
!Safety Concerns! : fire
A bimetallic strip (12”) of iron and aluminum is vertically fixed at one end to a board. The top end has a point that is free to move. The bimetallic strip is straight at room temperature. WHen heated with a blow torch, the strip curves due to differential expansion
This demonstrates the application of a bimetallic strip. THe coffee maker is disassembled to expose the bimetallic strip inside.
!Safety Concerns! : boiling water
Three materials, at 50 g each, are used to dynamically show the specific heat. Aluminum, iron, and lead are heated in a beaker of boiling water. After a few minutes, the materials are transferred to a plastic tray with indicator tracks and a bee’s wax sheet. The materials will slide down the bee’s wax respective tracks as far as their own specific heat content will carry them.
The value of a Calorie is measured by heating water with a bulb.
A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.
An electromagnet with a removable iron cap is suspended by a rod above the lecture table. The electromagnet is powered by two 1.5 volt "D" cell batteries. With the power off, the cap is brought in contact with the magnet. The magnet cannot hold the cap. The cap is again brought in contact with the magnet, and the power is turned on and off. Weights are then added to the cap. The magnet and cap can now hold upwards of 5 Kg. Weights are continued to be added until the cap breaks from the magnet. The magnetic domains are disturbed, and the magnet returns to its original conditions.
A soft iron core is placed inside a solenoid having several hundred turns of fine wire. The coil winding is connected to a loudspeaker. Audible results of the Barkhausen Effect are produced by slowly moving a permanent magnet toward the solenoid core. A loud rasping sound will be heard caused by the domains aligning themselves. Successive passes produce no sound until the polarity of the magnet is changed.
!Safety Concerns! : mains; cryogen
Liquid oxygen is poured between the poles of an electromagnet with a very strong magnetic field. Because liquid oxygen is paramagnetic it will remain suspended between the poles of the magnet. If the demonstration is repeated with liquid nitrogen, the nitrogen will just fall through the poles of the magnet.
!Safety Concerns! : mains
A small piece of aluminum is suspended from a thread between the poles of a 1.2 H coil. When power is applied to the magnet, the aluminum will align itself parallel to the magnetic field. This is because aluminum is paramagnetic.
!Safety Concerns! : mains
A small piece of bismuth is suspended from a thread between the poles of a 1.2 H coil. When power is applied to the magnet the bismuth will align itself normal to the magnetic field. This is because bismuth is a diamagnetic material.
!Safety Concerns! : mains
An iron bar is used to try to pick up some paper clips or thumbtacks. It is not able to do this because it is not magnetized. The rod is placed in a long solenoid and DC power applied. The rod becomes magnetized and is able to pick up some of the paperclips or tacks. The rod is again placed inside the solenoid and 110 VAC applied. This demagnetizes the rod and it will not pick up any tacks.
!Safety Concerns! : car battery
A solenoid is suspended vertically on two wooden blocks and hooked up to a car battery. When power is applied, the solenoid is barely able to support any weight. When an iron core is added, the solenoid is now able to support a much greater weight.
A small air core solenoid is connected through a switch in series to a 6 V power source. A length of wire is wrapped around the solenoid and connected to a projection ammeter. The switch is thrown and the meter reading is noted. An iron core is inserted in the solenoid and the demonstration is repeated. The meter reading is much greater with the iron core. Reversing the battery reverses the direction of the induced current.
!Safety Concerns! : fire; mains
A piece of iron is suspended with a copper wire at the height of one pole of a magnet to which it is attracted. The iron is then heated with a torch and eventually falls from the magnet. As the iron cools it will again be attracted to the magnet.
!Safety Concerns! : mains
A 25 VAC, 60 Hz signal is applied to a transformer primary. The voltage drop across a resistor in line with the primary is connected to the horizontal input of an oscilloscope. The voltage drop across a capacitor in the secondary is connected to the oscilloscope vertical input. The Hysteresis Curve of iron in a transformer core is then displayed on the scope.
A microwave transmitter emits a variable signal between 0.4-4.0 KHz. Two different probes are used to search the "E" and "B" fields. The "B" field probe is a single-turn loop used as a pickup coil. The "E" field probe is a shielded cable with about 5 cm of the center conductor exposed at its end. An oscilloscope with a sensitive preamp is used to see the effect of each probe.
A microwave transmitter emits a 10 GHz signal modulated by a 1000 Hz square wave from two adjacent horns. A microwave receiver is placed facing the two sources and can be moved parallel to their separation axis. The receiver is connected to an audio speaker to make the received signal audible. With one of the transmitter horns covered, the receiver picks up maximum amplitude when directly in front of the open horn. When both transmitter horns are uncovered, however, the receiver picks up maximum amplitude when facing the center of the two horns, thus demonstrating constructive interference. The received signal can also be displayed on an oscilloscope.
A microwave transmitter emits a variable polarized signal between 0.4-4.0 KHz. A receiver, connected to an audio speaker to make the received signal audible, faces the transmitter. A metallic grid, consisting of thin and closely spaced parallel bars, is held between them at various orientations. When the bars are held parallel to the E-field, the signal is blocked. When the bars are rotated 90 degrees, however, the signal is uninterrupted. A solid metallic sheet attenuates the waves. The output can also be displayed on an oscilloscope.
A 4-meter RF oscillator (Å80 MHz) is used with a dipole antenna to show polarization and standing waves. A small lamp at the center of the dipole glows brightly with the antenna held at antinode points parallel to the transmitter. If the antenna is rotated so that it lies perpendicular to the transmitting antenna, the bulb goes out.
Using a function generator and a microphone amplifier, the lecturer’s voice may be transmitted via antenna to an AM radio tuned to the same frequency.
Two bare copper wires, 5 m long and 20 cm apart, are stretched above the lecture tables. The wires are connected at one end to a 4-meter RF oscillator (Å80 MHz) and are shorted at the other end. Small incandescent bulbs with rigid wires protruding from their terminals can be placed over the parallel wires and slid along them. Standing electromagnetic waves on the wires can be demonstrated by sliding the bulbs along the wires and finding the nodes and antinodes.
To show that if some given microwave is transmitted between two aluminum parallel plates of variable separation, there is a critical separation distance below which an abrupt cut-off is noticed and no wave is propagated.
To show that if a short pulse is sent through a sufficiently long coaxial cable, the end condition will determine whether the waveform is reflected or terminated. This demo can also be used to calculate the speed of propagation of a wave in the coaxial cable.
This demonstration uses the same cable and pulse generator as K8. A resistor is added in series with the cable. The capacitance of the cable is used as the capacitor in the circuit. The reflected pulse is shown on an oscilloscope. The reflected pulse is first shown as a normal RC time constant trace. The scope sweep rate is then increased to a point where the RC curve is now seen as a series of "steps," each “step” being a pulse traveling back and forth in the transmission line.
!Safety Concerns! : radiation
A small microwave oven can be disassembled to show the inner parts.
A lost demo from the Demo Book circa 1980-2003
The internal resistance of the components in this LC circuit is sufficient to cause damping. The inductance of the coil can be changed by inserting an iron core and the capacitance of the decade capacitor can be varied to affect the rate of damping. An oscilloscope is used to display the damped wave.
A series circuit consisting of a decade resistor, a decade capacitor, and a variable inductor are driven by a square wave generator. The damped signal across any of the circuit's components can be displayed on an oscilloscope.
A long cable in series with a sine wave generator is wrapped several times around a 120 turn coil. An LC circuit is formed by adding a 2500 pF capacitor in series with the coil and an oscilloscope is used to monitor the signal across the capacitor. The frequency of the
Two coils are placed facing each other. One of the coils is connected to a sine wave generator and the other is in series with a capacitor. The driving signal in the first circuit as well as the voltage across the capacitor in the second circuit are monitored simultaneously on an oscilloscope. By changing the frequency of the generator, it is possible to pass through resonance and observe the increase in amplitude of the signal at that point. When the coils are moved apart, the resonant frequency drops.
Two coils are placed facing each other. Each of the coils are in series with a capacitor, the values of which have been chosen such that the two LC circuits have slightly different resonant frequencies. One of the coils is driven by a sine wave generator, the other is hooked up to an oscilloscope. When the voltage across the capacitor of the secondary coil is displayed on the oscilloscope, a beat frequency is observed as the mutual inductance is varied.
!Safety Concerns! : mains
A series circuit consisting of a large solenoid, a variable capacitor, and a large light bulb is connected through a knife switch to 120 VDC. The inductance of the solenoid varies with the insertion of an iron core. When some capacitance is chosen and the iron core is slowly inserted into the solenoid, the circuit will resonate at some point and the bulb will light up. This process is repeated for different values of the capacitor.
A series RLC circuit is driven by a sine wave generator. The applied voltage and the current through the circuit are displayed simultaneously on an oscilloscope. At resonance, both voltage and current are in phase. When the driving frequency is changed, however, a phase shift results. At frequencies above resonance, the current lags behind the voltage; below resonance, the current leads.
A series RLC circuit is driven by a sine wave generator whose output is swept over a frequency range below, through, and above the resonant frequency of the circuit. The swept resonance curve can be displayed on an oscilloscope and the effect of changing the values of one or more of the circuit elements can be shown.
A resistor is in series with a parallel LC circuit. The resulting RLC circuit is driven by a sine wave modulated with a square wave, the former being tuned to the resonance frequency of the circuit. The signal across the parallel LC portion of the circuit is shown on an oscilloscope. The driving frequency can be changed and the resulting change in the waveform above and below resonance observed.
Duplicate - See X280
!Safety Concerns! : laser
This one is nice. Trust me. The total internal reflection of a helium-neon laser beam within a water tank is demonstrated. The angle of incidence can be varied and the phenomenon observed as one passes through the critical angle.
Plexiglas rods bent into various shapes are illuminated at the end with a flashlight. Total internal reflection of the light within the rods makes it travel through the rods and emerge at the other end.
The image of printed words is transmitted through a bundle of approximately 25,000 coherent optical fibers. A lens is used to bring the image into the focusing range of a TV camera.
!Safety Concerns! : laser
Light from a helium-neon laser can be guided through two flexible light guides. One consists of 4000 coherent optical fibers and the other is made up of about 42,350 randomly-arranged fibers.
A number of reflection holograms can be set-up on the lecture tables. Students have to come up to the lecture tables to see them
A continuous spectrum is formed on the wall by shining white light into a prism. A second prism held next to the first makes the white light go straight through.
A single hollow prism as well as double compound hollow prisms can be filled with oil or other liquids to demonstrate various indices of refraction.
!Safety Concerns! : laser
A beam of light from a laser is directed at a tank of water and is refracted as it enters the water.
!Safety Concerns! : acid
A beam of white light is directed through a transparent vessel and projected on a screen. The vessel contains a mixture of water and sodium thiosulfate. Dilute sulfuric acid is added to the mixture. Colloidal sulfur begins to form and the beam passing through the liquid starts to look blue. As the number and size of the scattering particles increases, the transmitted light changes color from a bright white to yellow to orange, and then to red. Eventually even red light is no longer transmitted. It can also be shown that the light through the container becomes increasingly polarized in the process.
White light is directed at a circular flask of water representing a single drop of water. A rainbow is formed and seen on a wall. The rainbow can be shown to be polarized.
A small hole in a sheet of cardboard is illuminated strongly and its image projected on a screen. When a calcite crystal is placed over the hole, two spots of light appear on the screen. As the crystal is rotated, one spot stays fixed while the other moves around it. If a polarizing sheet is added to the path of the light and rotated, the two images may be made to disappear alternately.
Essentially the Rive Ray Box with arc lamp, slits and lenses on an unwieldy rotating stand. Last requested in 1989.
Light from a lamp passes through a series of slits forming a number of rays. A variety of lenses can be placed in the path to observe their behavior. Shown with a mounted overhead camera.
!Safety Concerns! : fluid; strobe
A ripple tank is placed on an overhead projector. Two synchronous point sources, whose frequency can be varied, tap the surface of the water and produce circular waves. The interference pattern of the waves including the lines of nodes can be observed on a screen.
A wide variety of striped patterns (straight parallel stripes, concentric circles, or radial lines) printed on transparencies can be overlapped on an overhead projector and the resulting Moiré interference patterns observed.
Two loudspeakers, driven by an audio generator, are placed on the lecture table facing the audience. When members of the audience move their heads from side to side and listen with one ear, they can experience the nodes resulting from the interference of the two sources.
Duplicate - see K2
A plano-convex lens of very small curvature is held with its convex side against a plane piece of glass, creating a thin film of air between the two. When white light from a carbon arc projector is shone at the apparatus and reflected on a screen, colored rings are observed. The pieces thickness of the film can be changed by adjusting the pressure between the pieces of glass, thus changing the ring pattern.
Two glass disks with approximately flat surfaces are placed on top of one another and illuminated with a source of monochromatic light. Straight parallel interference fringes are observed.
!Safety Concerns! : fluid
Large bubbles, 2 to 3 feet in diameter, can be made in front of the class. When illuminated with white light, interference colors are seen on them.
!Safety Concerns! : fluid
A beam of white light is directed at a thin film of soap and the reflection off this film is projected on a screen. The film is thinner at the top and interference bands of color are seen on the screen. The projected image is inverted due to the optics involved. As the film becomes thinner, no reflection is seen.
!Safety Concerns! : fluid
Like P8 but with turpentine.
!Safety Concerns! : laser
Different lasers are directed at slides of double slits and the resulting diffraction patterns are observed on a screen. See Q4 for slit width dependence.
!Safety Concerns! : fluid; strobe
A ripple tank is placed on an overhead projector. A horizontal ruler taps the surface of the water at a variable frequency and produces plane waves. The waves are incident on a barrier containing two adjustable openings. A double slit interference pattern is observed on the other side of the barrier.
!Safety Concerns! : laser
A small Michelson interferometer like those used in the Michelson-Morley Experiment and LIGO.
A beaker filled with water is placed on an electronic scale. A ball mounted on a stick is slowly brought into the beaker of water. The displaced water is trapped in a catch beaker. The displaced water is then weighed on the electronic scale to determined the buoyancy force. This shows that a body wholly immersed in a fluid is buoyed up with a force equal to the weight of the fluid displaced by the body.
This demonstrates Archimedes' principle of buoyancy, and the transmission of pressure through liquid.
A tank is filled with water. A plastic jar is weighed with sand so that it's just sinks to the bottom of the tank. When salt is slowly added, the plastic jar is buoyed upward. This shows Archimedes' principle of buoyancy.
A clear plastic U-tube is filled with colored water. A small amount of turpentine is added to one side of the U-tube. The difference in height between the two liquids can be easily measured. The less dense liquid (turpentine) will be at a higher elevation.
Four differently shaped glass vases with different volumes are securely sealed to a manifold. The glass vases are then filled with colored water. The liquid rises to the same level in all vases, no matter the shape of the vase.
A blower is attached to one side of a Venturi tube, which is filled with colored liquid. As air is blown through the tube, the liquid rises to different heights indicating that the pressure induced in the tube is not the same.
A ping pong ball can be balanced on an air stream from a blower.
Formerly called Mariotte's Bottle.
Two beakers are set at different elevations. The top beaker is filled with colored liquid. Clear plastic tubing connecting the two beakers is used to draw the liquid from the top beaker to the bottom beaker. The colored liquid can be seen flowing from the top beaker to the bottom beaker.
A vacuum pump is used to evacuate air from a 2 liter metal can. As air is evacuating, the can crushes into itself due to atmospheric pressure.
A small amount of water is poured into a 2 liter metal can. The can is heated using a blow torch or bunsen burner causing the water to boil. The can is then tightly sealed. As the steam cools down, a vacuum forms inside the metal can, thus the can collapses.
This apparatus has a ball float to hold gas and a gauge to indicate pressure. The gauge and ball float are connected by a tube. There is a valve near the gauge for letting gas in or out. The ball float is heated in a beaker of boiling water to show an increase in pressure. The ball float is then placed in a beaker of ice water. This demonstrates the relationship between temperature and pressure with a fixed volume of gas.
The apparatus consists of an enclosed cylinder and a piston assembly. The base of the cylinder has two transducers mounted on it. Sealed against the lower surface of the base is a pressure transducer. Mounted in the cylinder on the top of the base is the temperature sensor. As confined air in the cylinder is compressed, the resulting pressure, temperature, and volume can be seen graphically. The more rapidly the volume is changed the closer the process approaches being adiabatic, no heat transfer.
Various types of balloons when placed in a dewar of liquid nitrogen shrink in size (PV=NRT). The balloons will return to their original size when removed from the liquid nitrogen.
A clear plastic cup is filled with water. A piece of cardboard is placed on top of the cup. When the cup is overturned, the cardboard sticks to the cup and the water does not spill due to surface tension.
A buoy exhibits simple harmonic motion caused by a buoyant force.
!Safety Concerns! : fluid; strobe
A ripple tank is placed on an overhead projector. A horizontal ruler taps the surface of the water at a variable frequency and produces plane waves. The waves are incident on a barrier containing an adjustable opening and the resulting diffraction pattern is observed on the other side of the barrier.
!Safety Concerns! : laser
A laser is directed at an adjustable single slit and the resulting diffraction pattern observed on a screen. A Cornell "Slitfilm Demonstrator" slide, containing single slits of various widths, as well as commercial single slits made with razor blades (0.12, 0.25, and 0.50 mm wide), are also available.
!Safety Concerns! : fluid; strobe
The ripple tank is placed on a view graph. A strobe is used to measure the frequency of a motor with speed 1600RPM or ripples. Vernier calipers are used to measure separation between maxima.
!Safety Concerns! : laser
A laser is directed at a slide containing double slits of different widths and spacings, and the resulting diffraction patterns are observed on a screen. See P10 for wavelength dependence.
!Safety Concerns! : laser
A number of pinholes of various sizes on metal plates can be used with a laser to demonstrate the corresponding diffraction patterns.
A large board containing three rows of double pinholes faces the audience. A source of bright light directly behind the board illuminates the pinholes. The pinholes in each row have a separation of 5, 10 and 15 mm, respectively. Members of the audience sitting close to the board will distinguish the pinholes in each row as separate point sources. As the distance increases, the separation of adjacent pinholes becomes less distinct. At about 45 m, only the set with a 15 mm separation can be resolved.
!Safety Concerns! : laser
Transmission gratings with 7500, 13400, or 15000 lines per inch, as well as others with no available data can be used with a laser to show diffraction patterns.
!Safety Concerns! : laser
Two-dimensional diffraction patterns may be observed from two single slits, a periodic mesh, or two one-dimensional gratings.
!Safety Concerns! : laser
A 1" square zone plate, consisting of alternately trans-parent and opaque zones equal in dimensions to the Fresnel zones, is placed in the path of a divergent laser beam. The zone plate concentrates a large fraction of the light coming from one of its conjugate points upon the second, much as a lens does. As a result, the image of the beam is focused on a screen placed at an appropriate distance from the plate. This demonstration is not very visible in a large class.
!Safety Concerns! : laser
A beam of white light and a red laser beam are shone on a large reflection grating. The resulting zero-order reflection on the screen consists of a white spot and the red laser dot right above it. Higher orders of reflection, however, are made up of full color spectra with the red laser dot lying above the red part of the spectra. Uses a $3600 reflection grating from the George R. Harrison lab.
!Safety Concerns! : laser
A steel machinist's ruler is placed on a lab jack. The laser is adjusted so that it grazes the last two inches on the scale. The steel ruler acts as a reflection grating producing a series of bright spots on the wall. The distance to the wall and the distances between the spots can be measured with a meter stick.
!Safety Concerns! : HV; EMF
Duplicate - See R2
Duplicate - see N1
Gas discharge lamps filled with different gasses such as hydrogen, helium, mercury,neon, and argon can be looked at through a piece of replica transmission grating or a thin slit on an index card. Their corresponding line spectra can be observed. A regular incandescent lamp with or without a red filter placed in front of it can also be looked at through a thin slit.
!Safety Concerns! : fire
Sodium vapor is created by heating large rock salt crystals in the flames of multiple Meeker burners. Light from an arc lamp passes through the flames, then through a lens system and a prism to a screen. The absorption line of sodium is observed in the yellow region of the spectrum.
A large chart shows the continuous visible spectrum of light as well as bright line spectra and absorption spectra of various atoms and molecules.
!Safety Concerns! : motor
A disk is divided into colored sectors of various proportions. It is mounted on a motor shaft and illuminated with white light. When rotated at a high speed, the eye perceives white instead of the individual colors.
A box contains three incandescent lamps (red, green, and blue). The lamps can be turned on and off and their intensities varied individually. They are shown onto a translucent glass to demonstrate the addition of primary colors.
!Safety Concerns! : motor
A large disk, 3' in diameter, is mounted on a motor shaft. The disk is made up of a black portion, a white portion and several sets of black arcs of different radii. When rotated, each set of arcs traces out a circle which appears to be of certain color. Changing the speed of rotation varies the intensity of the colors. When rotated in the opposite direction, the order of the colors are reversed.
Two sheets of polarizing filters are held parallel to each other in front of an incandescent lamp. When the second filter is rotated relative to the first one, the amount of light passing through the filters gradually decreases until, at 90 degrees, no light is transmitted. A third filter held at an angle other than 0 or 90 relative to the other two lets light pass through.
Light from an incandescent lamp is shown onto an assortment of metallic and glass objects placed on the lecture table. Using a polarizing filter, it is shown that the light reflected off the glass objects is polarized, while the light reflected off the metallic objects is not. The light reflected off the varnished table top is also polarized.
A beam of white light from a carbon arc projector is directed at a stack of glass plates which can be rotated about a vertical axis. The light is reflected off the glass and onto a screen. A Polaroid filter is held in the reflected beam while the glass is slowly rotated. At Brewster's angle, the reflected light is shown to be polarized. This demonstration can also be done with a single sheet of glass.
A beam of white light is directed through a tank of water in which a few drops of milk have been added. The beam is polarized due to scattering. This can be shown with a large polarizer rotated in front of the beam.
!Safety Concerns! : encourages tobacco use
A number of lit cigarettes are held in front of a black screen and illuminated from below with white light. The light scattered from the smoke appears to be blue and is polarized. If the smoke is inhaled and then introduced into the light, the scattered white light will look white due to the absorption of moisture by the smoke and will no longer be polarized.
See N6
Two perpendicular polarizers block light. Adding a quarter wave plate restores transmission.
A bright beam of light is polarized and directed through a 4' glass cylinder filled with a super-saturated sugar solution. The plane of polarization of the light entering the solution is rotated by it through an angle that depends upon both the concentration and the thickness of the liquid traversed. Since the rotation is different for different wavelengths, there is rotational dispersion and different colors are seen along the tube, producing a spiral appearance. As the polarizer is turned, the whole spiral rotates like a barber pole.
A sheet of cellophane is sandwiched between two linear polarizers at an angle to one another and placed on an overhead projector. Interesting and beautiful patterns and colors are seen. By rotating the polarizers, the colors can be made to change. The cellophane can also be folded so as to create different thicknesses in different areas and, therefore, obtain various colors. The same demonstration can be done with mica.
A Lucite model of the teeth of a gear is sandwiched between two linear polarizers and placed on an overhead projector. Strain lines are seen when force is exerted on the gear.
An electronic window consisting of a liquid crystal emulsion spread between sheets of conductive plastic film can vary its transmission based on an applied electric field.
Duplicate - see K4
Duplicate - see K3
A black light is used to illuminate various fluids...they glow.
When a glass rod and silk are used to charge a zinc plate, ultraviolet light does not discharge the plate. A glass plate is used to stop the UV light to show the difference with the plate and without.
Light from a mercury arc lamp is passed through monochromatic filters onto a photocell generating a current. A potential is applied between the anode and the cathode until there is zero current-flow. The stopping potential is plotted against the light frequencies.
A tube filled with a mixture of mercury and neon allows to demonstrate at room temperature the quantum transitions which results when electrons of different speeds collide inelastically with mercury and neon atoms. By increasing the acceleration voltage, the transitions can be observed visually in form of a characteristic color change. It is also possible to plot a current versus voltage curve with a few maxima and minima. This is done by means of an X-Y recorder.
Approximately 70 mouse traps are set, each having a cork resting on a trigger. The traps are in a plastic mesh enclosure. One cork is dropped through the top of the mesh causing a "chain reaction" of all the traps.
!Safety Concerns! : radiation and dry ice possible
A small cloud chamber for viewing charged particle tracks.
The circular path taken by an electron beam in a magnetic field is used to determine the charge-to-mass ratio of an electron. Magnetic deflection of the circular beam can be altered by use of Helmholtz coils. One video camera displays the circular beam. The tube can also be rotated causing the beam to take a spiral path. This is displayed to the class by use of another video camera.
!Safety Concerns! : HV
A historical spark gap in a vacuum chamber forms a plasma tube. AKA Bell Jar with Sparks
!Safety Concerns! : HV
A vacuum tube with a phosphor screen and a magnet demonstrates the Lorentz force and the discovery of the electron. Also see G5.
This page contains a list of other demos run for as long as we have records.
A set of meter sticks with tips and fins to show coordinate systems, notation for in and out of the board, and vector operations.
A dome with strings leading to a hoop.
A wheel to show properties of circular motion.
A string is attached to a wooden apple. See B109.
This is a "mini-experiment", or "toy for students to learn with".
Mini-Experiment analyzing the static friction between two blocks of wood.
!Safety Concerns! : projectile
Drop a basketball with a tennis ball on top of it. The tennis ball goes flying.
!Safety Concerns! : projectile
A stack of four bouncy balls are dropped. The top ball is unconstrained so rebounds with high speed, hitting the ceiling.
Half of a magnet colored as if it is a North or South pole. A prop for a thought experiment.
A digital force platform (glorified scale) can be used to find the impulse of someone jumping on it or something falling on it (a chain). In B61 Box.
Mini-experiment involving yo-yos to demonstrate rolling with or without slipping.
A disk which rotates for a long time with an increasing frequency of sound.
A shape that rattles back when spun one way but not the other.
This is a "mini-experiment", or "toy for students to learn with".
A ball bearing rolls around a concave glass dish, exhibiting harmonic motion.
An vane rotating from the pressure of incident light.
A concave, silvered mirror with a radius of curvature of 52 cm and a diameter of 44 cm faces a box with an open face. The box contains a lamp hidden from the audience. The image of the lamp is formed on top of the box and can be seen by the people directly in front of the box. The whole set up can be rotated on a stool so as to cover all the audience. We can use the new convex mirror we bought for 8.03.
It's a large concave mirror.
The many iterations of laboratory assignments for MIT’s introductory physics courses.
The direct goal of this experiment is to study a "conical pendulum", and apply Newton's 2nd law to an object moving in a circular orbit. A round weight of mass m (the "mass") is attached to a rotating shaft by a spring; you will adjust the angular velocity of the shaft rotation, measure the radius of the circular motion of the mass, calculate the centripetal force from F = ma and use the results to find the force constant of the spring. To simplify the analysis of your results, assume that the mass of the spring can be neglected. AKA Circular Motion and Hooke's Law
Measure the height of recoil of an air track glider on an incline after compressing a spring to different lengths. This can also be used as an in-class demo of energy dissipation.
