WAEC - Physics (2017 - No. 41)
A lamp rated 100W, 240V is lit for 5hours. Calculate the cost of lighting the lamp if 1kWh of electrical energy cost N5.
N2.50
N3.20
N6.50
N9.60
Explanation
Power = 100W; Voltage = 240V; Time = 5 hours
Total energy used = Power x time = 100 x 5 = 500wh
converting to kwh, we have
\(\frac{500}{1000} = 0.5kWh \times N5 = N2.50\)
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