What it shows:

A superconducting material in the presence of an external magnetic field excludes that field from its interior. This is shown by levitating a magnet above a high-temperature superconductor.

What it shows:

Mechanical properties of some materials change dramatically with temperature. These changes have entertaining effects on everyday objects by taking them from room temperature 300K to the temperature of liquid nitrogen 77K.

How it works:

Place your everyday objects in a dewar of liquid nitrogen for several minutes (at least until the LN₂ stops boiling). Some examples to use:

1. Rubber gloves freeze solid and shatter on impact with floor.
2. Use a banana to hammer a nail into wood
3. Frozen...

Drum evacuated by vacuum pump; crushed by atmospheric bombardment.

What it shows:

With an air pressure of 10⁵ Nm^-2 at sea level, even a heavy duty oil drum will be crushed if it has nothing inside to balance the pressure.

How it works:

The screw cap on the drum is fitted with a vacuum pump connector. Simply turn on the pump and wait; it takes about 8 minutes to pump down, so you can carry on with what you were doing interrupted by various creaks and bangs as the drum's side walls begin to give....

Smoke cell under microscope; smoke particles seen bombarded by air molecules.

What it Shows

Brownian motion shows direct evidence of the incessant motion of matter due to thermal energy. Here we use the random bombardment of smoke particles by air molecules.

How it Works

The CENCO Brownian Movement Apparatus consists of a metal chamber with a glass viewing window on top and a lens on one side (see figure 1). Smoke from a piece of smoldering rope or match is drawn into the chamber through an inlet tube by squeezing the rubber bulb....

Simulation of molecular motion (Brownian, diffusion, etc.) with ball bearings on shaking table.

What it shows:

Two dimensional simulations of molecular dynamics and crystal structure using ball bearings. It can be used to show qualitatively the dynamics of liquids and gases, and illustrate crystalline forms and dislocations.

How it works:

The molecular dynamics simulator is more commonly known as a shaking table. It consists primarily of a circular shallow walled glass table that is oscillated vertically so as to vibrate and...

Food coloring in glycerine is mixed by turning a drum, then unmixed by reversing. Has entropy decreased?

What it shows:

Ink is squirted into a fluid and mixed in until it disappears. By precisely undoing the motions in the reverse direction, the ink becomes unmixed! The demonstration seems to defy thermodynamics in that it appears that entropy decreases, but in actuality the reversible mixing is made possible by insuring that the mixing/unmixing is done without turbulence.

How it works:

The space between two, transparent and concentric...

Compression of gas within bicycle pump heats gas; alternatively, syringe PV=nRT (w/ Mac TC read-out).

What it shows:

An adiabatic process is one where no heat enters or leaves a system. Here we compress a gas adiabatically inside a bicycle pump. The work done on the gas increases its internal energy, so increasing its temperature in accordance with the first law of thermodynamics.

Increase in internal energy dU = dW the work done on the system

How it works:

Instead of allowing the air out of a bicycle pump we've...

What it Shows

Hot fluid rises, cool fluid sinks. Here is a desktop convection cell modeling the processes in the atmosphere, oceans or stellar interiors.

What it shows:

The demonstration shows density fluctuations in liquids. These fluctuations are particularly spectacular near critical points. A binary fluid mixture of methanol (29% by weight) and cyclohexane (71%) becomes opalescent when heated up to its critical temperature (about 45˚C) ... the fluids become miscible above this temperature.

How it works:

The two fluids are sealed in a special vial, able to withstand elevated pressure. The fluids are immiscible at room temperature. When brought up to 45˚C, they become miscible...

The microcystaline structure of a steel wire changes from body-centered-cubic to face-centered-cubic as it is heated to red-hot.

What it shows:

Iron atoms are arranged in a body-centered cubic pattern (BCC) up to 1180 K. Above this temperature it makes a phase transition to a face-centered cubic lattice (FCC). The transition from BCC to FCC results in an 8 to 9% increase in density, causing the iron sample to shrink in size as it is heated above the transition temperature.

How it works:

A three meter length of iron...

Observation of phase changes with corresponding pressure changes.

A two ml. plastic microcentrifuge vial and a small shop vise are used together to melt dry ice.

Wear safety glasses for this demo. The vial can explode, or shoot out of the vice, from the pressure of liquid carbon dioxide. Set up a camera with a close shot of an empty vial before putting in a loaded vial.

Crush a pellet of dry ice to make pieces that fit into the vial. Place a couple of pieces in the vial, and snap the lid closed.

Immediately place the vial horizontally in the jaws of the vice,...

CO₂ and He balloons in liquid nitrogen.

What it shows:

Cooling a gas causes a proportional decrease in volume with the drop in absolute temperature. A gas such as helium, which remains close to ideal at low temperatures, shows a four-fold decrease in volume when taken from room temperature 330K to liquid nitrogen temperature, 77K. Carbon dioxide however, sublimes at 194.5K, so is solid at 77K. Oxygen liquefies at 90K (S.T.P.). A qualitative demonstration of these effects can be shown with gas filled balloons.

How it works:...

What it shows:

According to present accepted theory the Universe came into existence some 17 billion years ago as a Big Bang and is currently expanding. You can model the expansion of space in two dimensions using a balloon.

...

Laser and plastic lens with curvature to simulate bending of light by massive object.

What it shows:

Gravitational lensing is caused by the bending of light rays by the gravitational field of an intervening object. The effect is seen with the Sun, but is most spectacular when a whole galaxy acts as a lens to a cosmologically distant object, such as a quasar. Depending on the geometry of the alignment and the structure of the lensing galaxy, the image of the quasar is distorted into two or more distinct images, sweeping arcs or a complete ring. Here we model...

What it shows:

One of the more important discoveries in modern physics is the production of isotopes (both radioactive and stable) by the capture of neutrons. ¹ In this experiment the bombardment of silver by thermalized neutrons produces short lived radioactive isotopes of silver whose half lives can readily be measured. It can also be shown that bombardment by fast neutrons does not induce radioactivity because of the extremely low neutron cross sections involved. Using a Geiger counter in conjunction with a multichannel analyzer in the MCS (...