There are different ways to investigate methods of insulation. In this practical activity, it is important to:
To measure the specific heat capacity of a sample of material, in this case using a block of aluminium with a hole in it for a heater, and a smaller hole for a thermometer.
Record results in a suitable table. The one below shows some example results.
|Current (A)||Potential difference (V)||Initial temperature (°C)||Final temperature (°C)|
(38.0 - 15.0) = 23.0°C
time = (10 × 60) = 600 s
energy transferred (J) = current (A) × potential difference (V) × time (s)
energy transferred in the example = 10.80 × 3.65 × 600
= 23,652 J
mass of block in example = 1.00 kg
change in thermal energy = mass × specific heat capacity × change in temperature
Rearrange the equation:
(to 3 significant figures)
The actual value for the specific heat capacity of aluminium is 900 J/kg°C. The calculated value does not match exactly but it is in the correct order of magnitude.
The accepted specific heat capacity of aluminium is 900 J/kg°C. If the example results were for a block of aluminium, why is the experimental value different?
The experimental value is greater than the accepted value. This means that more energy was transferred than is needed for the aluminium alone. Some energy was transferred to the surroundings instead.
|Hot immersion heater and sample material||Burnt skin||Do not touch the heater when switched on. Position it away from the edge of the bench. Allow time to cool before packing away equipment. Run any burn under cold running water for at least 10 minutes.|