NTA Abhyas JEE Main2020PhysicsCommunication SystemPractice
In optical communication systems operating at 1200 nm , only 2 % of the source frequency is available for TV transmission having a bandwidth of 5 MHz . The number of TV channels that can be transmitted is 10 n . The value of n is
Correct answer
6
Step-by-step solution
The frequency of optical communication is given by, v = c λ or v = 3 × 10 8 1200 × 10 - 9 v = 25 × 10 13 H z But only 2 % of the source frequency is available for TV transmission. v ′ = 2 .5 × 10 14 × 2 % v ′ = 2 .5 × 10 14 × 2 100 v ′ = 5 × 10 12 Hz ∴ N u m b e r o f c h a n n e l s = v ′ b a n d w i d t h N o o f c h a n n e l s = 5 × 10 12 5 × 10 6 = 10 6