Communication Systems Test 01 Notes - Class 12

 Page 1


CBSE TEST PAPER-01 
CLASS - XII PHYSICS (Communication System) 
1. Name the type of the communication system in which the signal is discrete
and binary coded version of message or information?
[1] 
2. What is the purpose of modulating a signal in transmission? [1] 
3. What is the requirement of transmitting microwaves form one position to
another on the earth?
[1] 
4. A signal jumps from one level to another instantaneously.
 What will be its frequency?
[2] 
5. Sky has no limit but sky wave propagation has its limit. Explain why? [2] 
6. A transmitting antenna has a height of 50m. If radius of the earth is taken as
 6250 km. find the area covered by it?
[2] 
7. Define the term modulation index for A.M. wave. What would be the
modulation index for an A.M. wave for which the maximum amplitude is ‘a’
white the minimum amplitude is ‘b’?
[3] 
8. A T.V. tower has a height of 80m. By how much the height of tower be
increased to triple its coverage?
[3] 
9. An audio signal of amplitude one half of the carries amplitude is employed in
amplitude modulation. What is the modulation index? Hence define
amplitude modulation?
[3] 
10. An audio signal of 32kHz modulates a carrier of frequency 84MHz and
produces a frequency deviation of 96kHz.
Find (a) frequency modulation index
 (b) frequency range of the frequency modulated wave? 
[3]