HEAT EXPERIMENTS

THE PHYSICS SUPERMARKET
  1. Specific Heat
  2. Temperature Profile of a Room
  3. Absoption and Radiation
  4. Rate of Heat Energy Conduction
  5. The Refrigerator
  6. Latent Heat of Ice

1. Specific Heat

Students use a calorimeter to determine the specific heat of water. They then use the vlaue to determine the specific heat of a metal cube.

0-12 V DC Power supply, 0-5 A ammeter, 0-12 V voltmeter, -10 to 110 C thermometer, Calorimeter, Stop watch, Methylated spirits, 2cm metal cube  Top

2. Rate of Heat Energy Conduction

Using an interface and temperature sensors students use hot water in test tubes to determine how the rate of heat energy conduction depends on the temperature difference and the suface area. Students measure the temperature of the water inside the tubes and the air surrounding the tubes as the hot water cools. Rates of temperature change are determined and using the mass of the hot water and its specific heat, the rates of temperature change are converted to rates of heat energy conduction. These are graphed against temperature difference. Two test tubes are used simultaneously, one large and one small. The surface areas of the tubes that contact the water are calculated and conduction is determined for a constant temp difference and then graphed against surface area. This experiment is upper level of difficult and best done as a demonstration with the teacher then leading the analysis.

Computer interface, PC, Large and small test tubes with matching holed rubber stoppers, 2 0-50 C thermistors, 2 brass shims, 2 strips aluminium foil, 2 stands bossheads and clamps, Electric fan  Top

3. Temperature Profile of a Room

A temperature sensor is connected to the bottom, the middle and the top of a long stick that reaches the ceiling. Temperature is logged using an interface and a computer for about half an hour after the heater in the room is turned on. The change in temperature of the different parts of the room is discussed.

Computer interface, PC, 3 0-50 C temperature thermistors with long leads, Long length of dowel that reaches the ceiling  Top

4. Absorption and Radiation

In this experiment students investigate the effect of the colour of an object on the rate that it absorbs and radiates heat. Students fill painted drink cans with cold and warm water and log the temperature with an interface and a PC.

Computer interface, PC, Drink cans painted shiny silver and matt black, Bar radiator   Top

5. The Refrigerator

In this experiment students do a theoretical analysis of the temperature of the air inside a bicycle pump that is sealed, the plunger is pushed to compress the gas for a time and then suddenly released. Their predictions are checked by using a pump that has a temperature sensor screwed into the end which is connected to an interface and a computer. The pump is 'pumped up' a few times and then the pressure held while the computer draws the temperature versus time graph. The pressure in the pump is released and the graph shows that the temperature in the pump is less than the initial value. The findings are used to explain the operation a closed system refrigerator.

Computer interface, PC, Bike pump with an airtight thermocouple   Top

6. Latent Heat of Ice

Students use their microwave oven at home to determine the latent heat of fusion of ice.

Microwave oven, 500 mL measuring cup, 0 to 110 C Thermometer, Stopwatch, 6 identical plastic cups, Refrigerator  Top