Q. To cover a population of 20 lakh, a transmission tower should have a height … (Radius of earth = 6400 km, population per square km =1000)
A) 25 m
B) 50 m
C) 75 m
D) 100 m
Explanation
(b) Area of region covered $= \ \pi(2nR)$
In 1 ${km}^{2} = 1000\ people$
$\frac{1}{1000} \times 20 \times 10^{6} = 20 \times 10^{6} = A$
$\therefore 20 \times 10^{3} = \pi(2 \times h \times 6400)$
$\Rightarrow h = \frac{20 \times 10^{3}}{\pi \times 2 \times 6400} \approx 50\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.