Q 12-07-148JEE MainJEE Main 2018 (16 Apr, Shift 1)Easy
A power transmission line feeds input power at $2300\ \text{V}$ to a step-down transformer with its primary windings having 4000 turns giving the output power at $230\ \text{V}$. If the current in the primary coil of the transformer is $5\ \text{A}$ and its efficiency is $90\%$, the output current would be:
Answer: (A) $45\ \text{A}$
Input power: $2300\times5 = 11500\ \text{W}$. Output power: $0.9\times11500 = 10350\ \text{W}$.
$$I_s = \frac{10350}{230} = 45\ \text{A}$$
Solution by Sreeraj P, M.Sc Physics