Given parameters
Power rating of the device (P) = 500 W = 0.50 kW
Time for which the device runs (T) = 10 h
Energy consumed by an electric device can be obtained with the help of the expression for power,
P = W/T
Work done = energy consumed by the device
∴ Energy consumed = Power × Time
Energy consumed = 0.50 × 10
Energy consumed = 5 kWh
Hence, the energy consumed by four equal rating devices in 10 h will be
⇒ 4 × 5 kWh
= 20 kWh