Q 12-03-240JEE MainJEE Main 2020 (5 Sep, Shift 1)Medium
An electrical power line, having a total resistance of $2\ \Omega$, delivers $1\ \text{kW}$ at $220\ \text{V}$. The efficiency of the transmission line is approximately:
Answer: (D) $96\%$
Current $I = \dfrac{1000}{220} \approx 4.55$ A. Loss in the line $= I^{2}R \approx 4.55^{2}\times2 \approx 41$ W.
$$\eta = \frac{1000}{1000 + 41} \approx 96\%$$
Solution by Sreeraj P, M.Sc Physics