Question

two 220V, 60W bulbs are used for 5 hours a day for 10 days, if each unit (1 kilowatt hour) costs Rs 3.50, find the total expense for it? please solve with explanation

a) Rs 10.50 b) Rs 21 c) rs 38.50 d)rs 77

Answer 1

Total energy

$$E = N * t$$

Where $N$ – power, $t$ – the total time.

$$E = N * t = (2 * 60W) * (10 * 5h) = 6000 \, Wh = 6 \, \text{kilowatt hour}$$

The total expense = cost* total energy:

$$TE = 6 * 3.50 = Rs \, 21$$

Answer: b) Rs 21.