WAEC - Physics (2021 - No. 31)
In the diagram above, a bulb is lit by drawing 2.0A from 440V a.c. source. Calculate the cost of keeping the bulb on for two days at $0.40 per kilowatt-hour .
$16.90
$84.48
$1690.00
$8.48
Explanation
Power[p] = IV → 2 * 440 = 880Watt
Energy = p * t = 880 * 48hrs
= 42240 or 42.24kwh
But 1 kwh cost $0.40
∴ 42.24kwh costs 42.24 x 0.40
= 16.896 or $16.90
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