Q 12-08-195JEE MainJEE Main 2019 (10 Jan, Shift 1)Easy
A TV transmission tower has a height of $140\ \text{m}$ and the height of the receiving antenna is $40\ \text{m}$. What is the maximum distance up to which signals can be broadcasted from this tower in LOS (line of sight) mode? (Given: radius of earth $= 6.4\times10^6\ \text{m}$)
Answer: (D) $65\ \text{km}$
$$d = \sqrt{2Rh_T} + \sqrt{2Rh_R} = \sqrt{2\times6.4\times10^6\times140} + \sqrt{2\times6.4\times10^6\times40}$$
$$d = 42.3\ \text{km} + 22.6\ \text{km} \approx 65\ \text{km}$$
Solution by Sreeraj P, M.Sc Physics