A heater has a power rating of 1200 W. the heater is left on for 5 minutes & makes 2.88 x 100000 J. efficiency

Question

i want to know the efficeny of this heater.

Answer 1

Power is measured in watts, W. It has dimensions joules per second. By multiplying the power rating by the time the heater is on in seconds you will get the energy output in joules. If you divide the actual output by the expected output, then multiply by 100 you will get percentage efficiency, in this case 80%.

Answer 2

luke is correct.

However, an electric heater has 100% efficiency, as all of the electric power it uses is changed to heat.