# Physics Class-12 Chapter-15 Communication system Most VVI Objective Questions

Q.1. The optical fibre works on the principle of

(A) Scattering

(B) Refraction

(C) Dispersion

(D) Total internal reflection

Ans:- (D)

Q.2. The value of amplitude modulation index is

(A) always zero

(B) between 1 and ∞

(C) between 0 and 1

(D) always ∞

Ans:- (C)

Q.3. Which frequency range is used for TV transmission ?

(A) 30Hz-300Hz

(B) 30kHz-300kHz

(C) 30MHz-300MHz

(D) 30GHz-300GHz

Ans:- (C)

Q.4. The height of a TV transmission tower at any place on the surface of the earth is 245 m. The maximum distance up to which transmission of tower will reach is

(A) 245 m

(B) 245 km

(C) 56 km

(D) 112 km

Ans:- (C)

Q.5. Sky wave communication is based on

(A) reflection by ionosphere

(B) absorption by ionosphere

(C) transmission through ionosphere

(D) none of these

Ans:- (A)

Q.6. In optical fibre communication light source is

(A) zener diode

(B) laser or LED

(C) photodiode

(D) sodium lamp

Ans:- (B)

Q.7. Name the types of communication system according to the mode of transmission.

(A) Analog of communication system

(B) Digital communication system

(C) Both A and B

(D) none of these

Ans:- (C)

Q.8. A network within an institution is known as

(A) internet

(B) local area network (LAN)

(C) Computer system

(D) computers network

Ans:- (B)

Q.9. For radio waves ionosphere acts as a

(A) rarer medium

(B) denser medium

(C) free space

(D) dielectric medium

Ans:- (A)

Q.10. Which is not an example of analog communication ?

(A) FAX

(B) telegraphy

(D) telex

Ans:- (A)

Q.11. Name the device which can represent  digital data by analog signals and vice-versa.

(A) Modulation

(B) Demodulation

(C) Modern

(D) none of these

Ans:- (C)

Q.12. The essential components of the communication system are

(A) transmitter

(B) channel

(D) all of above

Ans:- (D)

Q.13. The range of TV transmission can be increased by using

(A) small antennas

(B) tall antennas

(D) none of these

Ans:- (B)

Q.14. The device that is ‘duplex’ is

(A) TV

(B) mobile

(C) both ‘A’ and ‘B’

(D) none of these

Ans:- (B)

Q.15. The process opposite to modulation is

(A) Demodulation

(B) transmission

(C) remote sensing

(D) Fax

Ans:- (A)

Q.16. For television broadcast which type of modulation is used for audio signal ?

(A) amplitude modulation

(B) pulse modulation

(C) frequency modulation

(D) none of these

Ans:- (C)

Q.17. The loss of strength of a signal as it propagates through the communication channel is called

(A) antenna

(B) digital system

(C) attenuation

(D) none of these

Ans:- (C)

Q.18. The maximum percentage of deformationless  modulation is

(A) 100%

(B) 75%

(C) 110%

(D) 50%

Ans:-(A)

Q.19 Which of the following is not a transducer ?

(A) land speaker

(B) amplifier

(C) microphone

(D) all of the above

Ans:- (B)

(A) Omni directional type

(B) vertical type

(C) horizontal type

(D) none of these

Ans:- (B)