Question

Suppose in a house there are four bulbs of 100 W each, six of 60 W each and six of 40 W each. All of them are used for two hours a day. How many units of electricity will be used up in 30 days? How much will they have to pay at Rs. 2.80 /- per unit?

Answer 1

Total power used by 4 bulbs of 100 W each , six bulbs of 60 W and six bulbs of 40 W
= (4 x 100W) + (6 x 60 W) + (6 x 40 W)
= 1000 W = 1 kW.
Total electrical energy consumed per day
= 2 hrs x 1 Kw = 2 kWh
In 30 days, energy consumed
= 2 x 30 kWh = 60 kWh
The cost of the total enegy consumed is
=Rs. 2.80 x 60 = Rs. 168/-
Thus, the total power used in 30 days is 60 kWh and the electricity bill for 30 days will be Rs. 168.