Alternating Current - Result Question 35
37. A 220 volts 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
[2010]
(a) 3.6 ampere
(b) 2.8 ampere
(c) 2.5 ampere
(d) 5.0 ampere
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Answer:
Correct Answer: 37. (d)
Solution:
(d) $\frac{V_2}{V_1}=0.8 \frac{I_1}{I_2} \Rightarrow \frac{V_2 I_2}{V_1 I_1}=0.8$
$V_1=220 V, I_2=2.0 A, V_2=440 V$
$I_1=\frac{V_2 I_2}{V_1} \times \frac{10}{8}=\frac{440 \times 2 \times 10}{220 \times 8}=5 A$
