A `220 V` input is supplied to a transformer. The output circuit draws a current of `2.0 A` at `440 V`. If the efficiency of the transformer is `80%`, the current drawn by the primery winding of the transformer is

Options

A. 2.5 A
B. 5A
C. 10A
D. 7.5A

Answer

B

Explanation

Power output `(P_o)= VI=440 xx 2`
Input power `(P_i)=220 xx I`
`:. Eta = (P_o)/(P_i) :. 8/10 = (440 xx 2)/(220I) = 4/I`
`:. 8I = 40 :. I = 5A`.