JEE Main201910 Jan 2019Morning ShiftPhysicsCommunication SystemActual
A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m . What is the maximum distance upto which signals can be broadcasted from this tower in LOS (Line of Sight) mode? (Given: radius of earth = 6.4 × 10 6 m ) .
Options
- A48 k m
- B40 k m
- C80   k m
- D65 k m
Correct answer
D. 65 k m
Step-by-step solution
D = 2 h T R + 2 h R R D = 2 × 140 × 64 × 10 5 + 2 × 40 × 64 × 10 5 D = 8 × 10 3 [ 28 + 8 ] D = 8 × 10 3 [ 2 7 + 2 2 ] D = 16 × 10 3 [ 7 + 2 ] D = 16 × 10 3 2.6 + 1.4 = 64000 m = 64 k m ≃ 65 k m