Q 12-08-098JEE MainJEE Main 2023 (11 Apr, Shift 1)Easy
A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at $4\ \text{km}$ distance from it is $x\times10^{-2}\ \text{m}$. The value of $x$ is ______. (Let radius of earth $R=6400\ \text{km}$)
Answer: (A) 125
$d=\sqrt{2Rh}\Rightarrow h=\dfrac{d^2}{2R}=\dfrac{16\times10^6}{1.28\times10^7}=1.25\ \text{m}=125\times10^{-2}\ \text{m}$.
Solution by Sreeraj P, M.Sc Physics