A lamp rated 100W, 240V is lit for 5hours. Calculate the cost of lighting the lamp if 1kWh of electrical energy cost N5.

A. N2.50
B. N3.20
C. N6.50
D. N9.60

Correct Answer: Option A

A. N2.50

Explanation

Power = 100W; Voltage = 240V; Time = 5 hours

Total energy used = Power x time = 100 x 5 = 500wh

converting to kwh, we have

500/1000=0.5kWh×N5=N2.50