This is a homemade mechanical apparatus built for the use with the overhead projector (see top picture). The apparatus consists of a black, rectangular box with vibrating metal plate and clear plexiglass lid and bottom. There is a handful of metal balls of different sizes inside the box. The frequency of vibration (the intensity of chaotic motion) is controlled by the Variac. The bottom photo is the picture seen by the audience.

Note: The device should be angled so that when at rest the balls will settle along the metal plate. Also, it should be leveled so the "molecules" are equally distributed along the plate.

The instructor could burn one paper cup and boil water in another. Use a small paper cup with a flat bottom (no edge ring) and fill it with water almost to the top. Place it on the wire mesh over the flame of the Bunsen burner as shown in the picture. The water in the cup will boil but the paper will not ignite.

Note: paper is ignited at 233°C

Six metal spokes composed of metals with different heat conductivities are mounted on a central hub. Wax balls are attached to each of their ends and a Bunsen burner is placed below the hub. The balls will fall in a sequence, according to heat conductivity of individual rods. Alternatively, 1/4-1/2" steel balls glued to the rods with wax can be used to produce a louder effect.

List of parts:

1. Metal rod apparatus
2. Wax
3. Six 1/4-1/2" steel balls
4. Bunsen burner
5. Sparker

Note: Use a hot water bath to melt the wax.

Two related experiments are available:

Expanding Ball and Ring: At room temperature, the ball fits through the ring. When heated, the ball will no longer pass through.

Bimetalic Strip: made by welding together thin strips of brass and steel. These metals have different coefficients of thermal expansion. The strip curls when heated and re-straightens when cooled.

List of parts:

1. Ball and ring
2. Bimetalic strip
3. Bunsen burner
4. Spark lighter
5. Beaker of water
6. Liquid nitrogen (optional)

When a lit candle is placed under one clear chimney and a source of smoke (incense or punk) is placed above the other clear chimney, convection currents can be seen.

Note: The box demensions are 5"x8"x5". Use a camera for larger classes.

Two parabolic mirrors are placed a couple of meters apart. The instructor puts a thermometer in the focus of one of the mirrors, and a heat source (a light bulb) in the focus of the other, and observe that the thermometer reads an increase in temperature. This result is trivial and expected by students. Now replace the heat source with a cold source (copper ball filled with liquid nitrogen) and notice the thermometer shows a decrease in temperature. Instructor can ask students if we are dealing with a "beam of cold", and discuss the second law of thermodynamics. This demonstartion can explain some phenomena (for example, morning frost, etc.)


Note: Mirrors should be precisely aligned. For alignment look through the stainless steel tube and make sure you see the focus of the thermometer in the focus of the distant mirror. For reading the temperature, use the big screen LCD thermometer.

Four vanes (one side white, one black) are suspended on a pin. When light is shined on the apparatus, vanes rotate in the direction of their white sides.

List of parts:

1. Radiometer
2. Light source with power supply

Notes:

• The vanes spin because the black surfaces are hotter than the white ones, so they give off more energy to air molecules. It has nothing to do with radiation pressure.
• Use the Variac to vary the light intensity.

This demonstration requires at least 20 minutes of lecture time. The setup is shown in the picture below.

Procedure:

1. A Petri dish half-filled with water is placed inside of the vacuum jar on a piece of thermally insulating material (styrofoam). Water evaporates very fast during evacuation, which can be harmful for the vacuum pump. To keep the pump safe, a water vapor trap is installed between the jar and the pump (see picture). This trap is a three-neck flask filled with blue Drierite crystals (Anhydrous Calcium Sulfate). When the Drierite crystals change color to pink, they do not absorb water any more and must be replaced.
2. When the pump is turned on the water should start boiling at about 28mm Hg. Then in 5-10 minutes ice will form on the surface but water will continue to boil below it.

List of parts:

1. Large bell jar
2. Aluminum base and rubber pad
3. Petri dish
4. Three-neck flask filled with drying agent
5. Vacuum pump and hoses

This demonstration requires time and effort to setup, but is easy to perform in an auditorium with the help of a student. A constant volume of air is heated continuously and a large water manometer measures its pressure. The instructor can obtain a roughly accurate plot of the isochor process [ p_t = p₀( 1+1/273.15 T ) ] and extrapoloate it to absolute zero.

List of parts: 500 mL round bottom flask with rubber stopper and glass tube inserted Crystallizing dish Thermocouple inserted in water Bunsen burner Water manometer connected to the 500 mL flask Large digital thermometer Procedure: Fill the crystalizing dish about half way with water and place it on the ring stand clamped to a long metal rod. Place the Bunsen burner under the dish. Clamp the flask to the rod and lower it into water. Fasten the long ruler to the metal rod that is clamped to the table. Thread the string up through the screw eyes. Tie it to the lower clamp. Fill the tube with colored water until the water level reaches the plastic rod holding the left sleeve of the tube. This plastic rod is a mark for constant volume during the experiment. Connect the plastic tube to the rubber stopper. Cork the flask tightly. Start heating the water in the crystallizing dish with the burner. As the pressure increases, pull the plastic tube up (by pulling the string) to keep the volume constant. With the help of a student, make a T-P(T) table and draw the graph.

A brass cylinder with a small amount of water sealed in by a rubber cork is quickly rotated by an electric drill. When the cylinder is squeezed by the wooden clamp (see the picture) the applying friction heats the water. In 1 to 2 minutes the water starts boiling and shoots the cork out of the tube.

A special flask holding boiling water produces steam that shoots out of the angled nozzles causing the flask to spin around.

Procedure:

1. Fill flask to about 1/2 inch below nozzles. Seal the neck with a cork.
2. Mount flask on the rod using test tubes as bearings as shown.
3. Boil the water with the Bunsen burner. When enough steam is produced, the flask will spin. Don't let it run out of water.

List of parts:

1. Hero's engine apparatus
2. Base and rod
3. 2 three finger clamps
4. 2 short test tubes
5. Bunsen burner and sparker

A working miniature version of the stirling cycle hot-air engine. Heat is supplied by a built-in alcohol burner.