Conversion of electrical energy to heat energy

Many homes have immersion heaters for heating the water and the two examples given here show how the heating effects of immersion heaters can be calculated. The first example uses a 50 W heater, you have probably used one in school and the second is a 3 kW immersion heater heating water for a bath.

Assuming that the all the electrical energy produced is converted to heat energy we can write:




But:
Heat energy = mass x specific heat capacity x temperature change and
Electrical energy = Volts x Amps x time = Electrical Power x time

Therefore:



In this example it has been assumed that all the heat given out by the heater has been absorbed by the aluminium, in fact some will be lost to the air.