### Physics - Principles of Communication

#### Question - 1

The distance between consecutive minima on a trasmission line is given by

• A $\lambda$
• B $\frac { \lambda }{ 2 }$
• C $\frac { \lambda }{ 4 }$
• D $\frac { \lambda }{ 8 }$

#### Question - 2

Repeaters are required every 40-50 km in a microwave terrestrial communication system because

• A the curvature of the earh limits the distance over which lin-of-sight can be established
• B microwave power decreases rapidly with distance
• C signal-to-noise ratio decreases rapidly with distance
• D signal distrortion creeps in rapidly with distance.

#### Question - 3

A modulator

• A generates constant frequency radiowaves
• B generates variable frequency radiowaves
• C improves signal-to-noise ratio
• D improves thermal stablity

#### Question - 4

In an AM waveform, the amplitude of side band is

• A independent of modulation index
• B independent of carrior amplitude
• C dependent on the amplitude of carrier wave only
• D dependent on the amplitude of carrier

#### Question - 5

A short circuited, uniform, lossless transmission line of 0.04 wavelength long, acts almost like an ideal

• A capacitor
• B inductor
• C series resonant circuit
• D parallel resonant circuit

#### Question - 6

The standard broadcast FM signal occupies a band width of about

• A 15 kHz
• B 53 kHz
• C 75 kHz
• D 200 kHz

#### Question - 7

A commonly used in-band signalling frequency is

• A 400 Hz
• B 1000 Hz
• C 2400 Hz
• D 3825 Hz

#### Question - 8

In AM, total modulation index must not exceed unity or else

• A the system will fail
• B distortion will result
• C amplifier wil be damaged
• D resonant waves will be generated

#### Question - 9

In a frequency modulation system the number of important sidebands depends on

• A the deviation alone
• B the modulation frequency alone
• C the modulation index alone
• D the modulating frequency and the modulation index

#### Question - 10

Which of the following systems is NOT analog?

• A Pressure gauge
• B Clinical thermometer
• C Trasistor radio receiver
• D Ordinary electric switch