What would be the expenditure in 30 days at the rate of 75 paise per unit, if a bulb of 100 W is used five hours per day?

A : Rs. 10

B : Rs. 7.5

C : Rs. 15

D : Rs. 11.25

General Science

Physics

Work Power Energy

Answer

Option 4 : Rs. 11.25

Explanation

1 Unit of electricity = 1 kWh = 1000 Watt-hour = 3.6 × 106 J

1 Kilo-watt = 1000 Watt

100 W = 0.1 kW [∵ 1kW = 1000 W]

In 30 days total consumption of the bulb = 0.1 kW × 30 days × 5 hours/day = 15 kWh

Given, cost of 1 unit = 75 paise

So total expenditure = 75 × 15 = 1125 paise = Rs. 11.25