1A20.10 Gaussian distribution
Steel balls run through a plastic maze on the overhead projector. At the bottom they will fall into a Gaussian distribution.
[Setup time: 2 min.]
1A30.40 Chalkboard globe
Draw chalk lines on a black globe to demonstrate non-flat topology, or trace a pencil parallel to the surface to show phase accumulation.
[Setup time: 2 min.]
1J40.20 Torque apparatus
A hanging beam has masses at both ends and at the center. When the balance is disrupted by adding weight, there is a net force on the balance, causing it to tilt.
[Setup time: 5 min.]
1K20.30 Static vs. Kinetic friction
A large cooler filled with bricks is difficult to start moving across the floor, but not as difficult to keep moving.
[Setup time: 5 min.]
1L20.10 Orbits on a membrane
A large weight makes a depression at the center of a rubber membrane. Steel balls can be rolled around to show orbits.
[Setup time: 10 mins.]
1N22.10 Fire extinguisher
Sit on a cart and shoot a fire extinguisher, propelling yourself in the opposite direction. Or, sit on the cart and blast the extinguisher at a side wall of the same cart, and show nothing happens. You must wear a helmet (provided) to operate this demo. Ear plugs, and having a student catch you before the cart hits the wall, are highly recommended.
[Setup time: 10 mins.]
2B60.60 Hydraulic Ram (Water Hammer)
A large quantity of water falling a small height pumps a small quantity of water a large height. The action is accomplished by creating a backward-propagating shock wave in the water about once per second. This demo is very entertaining.
[Set-Up Time: 10 min.]
3A70.10 Wilberforce pendulum
A mass with a large torsional moment hangs from a spring. Energy is transferred between vertical and torsional modes.
[Setup time: 2 min.]
3A75.10 Coupled harmonic oscillators (Normal modes)
Two or three riders on the air track are connected with springs to each other and to the air track frame. Normal modes can be excited by hand.
[Setup time: 15 mins.]
3A95.45 Jump phenomena
A rider on the air track is driven sinusoidally but the restoring force (rubber bands) does not quite obey Hooke's law. This yields Duffing's equation rather than the familiar linear oscillator equation. The system exhibits jumps between high and low amplitude when crossing over the resonance.
[Setup time: 25 mins.]
3A95.60 Parametric resonance of a pendulum
The pivot of a pendulum is driven vertically at a variable rate. Driving at twice the pendulum's natural frequency excites the system into resonance.
[Setup time: 20 mins.]
3B50.40 Moire Transparencies
Transparencies with a circular wave pattern can be overlayed to show interference patterns.
[Setup time: 2 mins.]
4F10.10 Unmixing
Glycerine between two concentric cylinders is injected with a pattern of dye. When the inner cylinder is rotated, the pattern disappears, but when the turning is reversed the pattern re-appears! A very dramatic demonstration of the role of time and randomization in entropy.
[Setup time: 30 min.]
5B10.40 Electric Field Display
A new apparatus has small particles (Splenda) suspended in oil between several pairs of electrodes. When voltage is applied, the particles align with the field lines. Shows point-point, point-plate, and plate-plate patterns. The apparatus is displayed with an overhead projector.
[Set-Up Time: 15 min.]
5D10.20 Playdoh Resistor
A lump of playdoh is connected to an ohmmeter, or in a series circuit. Molding it into various shapes changes its resistance in real time.
[Setup time: 15 mins.]
5G10.20 Break a magnet
It is very hard to remove the core of a strong horseshoe magnet.
[Setup time: 2 min.]
5G30.20 Paramagnetism of (liquid) oxygen
A metal container is filled with liquid nitrogen; liquid oxygen condenses on the outside and drips off the bottom and into the gap between the poles of a magnet. The oxygen droplets will get caught and stay in the field.
[Setup time: 10 mins.]
5H35.15 Birefringence on the overhead
A calcite crystal over a sheet with large lettering makes a double image. Each image has a different polarization.
[Setup time: 5 mins.]
5K20.25 Eddy Current Tubes
A strong magnet is dropped in plexiglas and copper tubes. In copper, the fall takes several seconds - even though the ball never touches the sides of the tube!
[Setup time: 5 mins.]
5K20.50 Shaded Pole Motor
An aluminum can is arranged in an AC magnetic field. When a phase modulation is introduced by the presence of another conductor, the can spins.
[Set-Up Time: 10 min.]
5L20.10 RLC, RC, RL Circuits
Connect an inductor, capacitor, and resistor mounted on a wooden board. Connect in series with a function generator and measure across the resistor with an oscilloscope. As the function generator sweeps over the resonance, the waveform grows and shrinks on the scope. Or, connect L and C in parallel to show a resonance dip. Or use RL or RC alone to show monotonic frequency dependence and find f3dB points.
[Setup time: 15 mins.]
5M20.10 Gaseous Discharge Tubes
Six discharge tubes with successively smaller levels of vacuum are excited with the Tesla coil. Show Crookes dark space, negative glow, glass phosphoresence.
[Setup time: 5 min.]
6A44.? Bucket of Light
A laser beam follows the arc of a stream of water, and is not "released" until it reaches the collection bucket.
[Set-Up Time: 15 min.]
6F40.10 Sunset
A few drops of milk in a beaker of water is illuminated from the back with a flashlight. Color scattering is observed.
[Setup time: 10 mins.]
6B40.35 Good Radiator/Bad Radiator
A white tile with a black circle on it is heated in a furnace until glowing. The black circle glows brighter than the surrounding tile.
[Set-Up Time: 30 min.]
6H30.40 Rotation dispersion in corn syrup
A beaker of corn syrup is placed between crossed polaroids on the overhead. The corn syrup changes colors as the second polaroid is rotated.
[Setup time: 10 mins.]
6H30.80 Faraday Effect
Polarized laser light passes through a solenoid filled with toluene. When the solenoid is turned on, the polarization of the outgoing beam is rotated proportionally to the strength of the magnetic field.
[Setup time: 15 mins.]
7A30.10 LEDs in Liquid Nitrogen
Bright LEDs of various colors are dunked in liquid nitrogen. Dramatic color changes, and increased brightness, are visible.
[Setup time: unknown]
7A60.50 Bragg diffraction with microwaves - improved apparatus
X-ray crystallography scaled up to centimeter wavelengths. The microwave source and detector are constrained to the same angle of incidence, which can been easily read off the device. The detector is attached to an audio speaker, through which the detected amplitude can be heard. As the beam angle is varied, or the crystal is rotated, distinct peaks are audible. A cubic crystal is currently available; different structures can be made upon request.
[Setup time: 10 mins.]
7B13.50 Fluorescent UV Beads
Special beads appear white, but they fluoresce bright colors after being exposed to UV light.
[Setup time: 5 mins.]
