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Question
Calculate the cost of operating a heater of 500 W for 20 hours at the rate of Rs 3.90 per unit.
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Solution
Power rating of the heater, P = 500 W
Duration of the operation, t = 20 hours
Electrical energy consumed = P × t
= 500 W × 20 hours
= 10000 W
= 10 kW
Rate for 1 kW = Rs. 3.90
Total cost of operating = Units consumed × Rate
= 10 × Rs. 3.90
= Rs. 39
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