Energy consumed by an electric heater can be obtained with the help of the expression,
P=WT
where, power rating of the heater, P= 1500 W=1.5 kW
time for which the heater has operated, T= 10 h
Work done = Energy consumed by the heater
∴Energy consumed =Power×Time =1.5×10=15 kWh
Hence, the energy consumed by the heater in 10 h is 15 kWh.