Q 12-03-109JEE MainJEE Main 2024 (31 Jan, Shift 2)Medium
By what percentage will the illumination of the lamp decrease if the current drops by $20\%$?
Answer: (C) $36\%$
Illumination is proportional to the power $P = I^2R$. With $I' = 0.8I$, $P' = 0.64P$, a decrease of $36\%$.
Solution by Sreeraj P, M.Sc Physics