A 4.5-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

The electrical energy is 13.5 kWh or 48600 kJ

Explanation:

Given that,

The power of the resistance heater, P = 4.5 kW

The water heater runs for 3 hours to raise the water temperature to the desired level.

We need to find the amount of electric energy used in both kWh and kJ.

Energy = Power × time

E = 4.5 kW × 3 h

= 13.5 kWh

Since,

1 kWh = 3600 kJ

13.5 kWh = 48600 kJ

Hence, the required electrical energy is 13.5 kWh or 48600 kJ