THE PHYSICS SUPERMARKET
- Specific Heat
- Temperature Profile of a Room
- Absoption and Radiation
- Rate of Heat Energy Conduction
- The Refrigerator
- 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
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
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