Energy consumed by an electric heater can be obtained with the help of the expression P= W/T.
Power rating of the heater (P) = 1500
W = 1.5 kW = 1500 W
Time for which the heater has operated (T) = 10 h
Work done = Energy consumed by the heater
∴ Energy consumed = Power × Time
Energy consumed = 1500 × 10
Energy consumed = 15000 W
Hence, the energy consumed by the heater in 10 h is 15 kWh.