Question

A landlord has eight 40W electric light bulbs, four 60W bulb and two 100Wbulb in his house. If he has all the points on for five hours daily and if NEPA charges 5k per unit. Calculate his bill for 30 days.

Answer 1

Power of 40W bulbs - 40W x 8 = 320J

Power of  60W bulbs -  60W x 4 = 240J

Power 100W bulbs - 100 x 2 = 200J

Total Power = 320 + 240 + 200 = 760W

We need to find energy so,

E = P x T

E = 760 x 5

E = 3800J

This is only the energy consumed in one day, for 30 days,

3800 x 30 = 114000J or 114KJ

So your final answer is: 114 kilo joules / 114KJ