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A 220-volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is 80%, the current drawn by the primary windings of the transformer is
A
5.0 ampere
B
3.6 ampere
C
2.8 ampere
D
2.5 ampere
Detailed Solution
Efficiency $\eta = \frac{\text{output power}}{\text{input power}} = \frac{E_2I_2}{E_1I_1}$
Output power = $440\times2.0 = 880$ W
Input power = $\frac{880}{0.80} = 1100$ W
$I_1 = \frac{\text{input power}}{E_1} = \frac{1100}{220}$
$I_1 = 5.0$ A
Output power = $440\times2.0 = 880$ W
Input power = $\frac{880}{0.80} = 1100$ W
$I_1 = \frac{\text{input power}}{E_1} = \frac{1100}{220}$
$I_1 = 5.0$ A