A 4-kW electric heater runs for 2 hours to raise the room temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

Q' = 8 KW. h

Q'=28800 KJ

Explanation:

Given that

Heat Q = 4 KW

time, t = 2 hours

The amount of energy used in KWh given as

Q ' = Q x t

Q' = 4 x 2 KW. h

Q' = 8 KW. h

We know that

1 h = 60 min = 60 x 60 s = 3600 s

We know that W = 1 J/s

The amount of energy used in KJ given as

Q' = 8 x 3600 = 28800 KJ

Therefore

Q' = 8 KW. h

Q'=28800 KJ