The output transducer of the communication system converts the radio signal into ________.

(a)

Sound

(b)

Mechanical energy

(c)

Kinetic energy

(d)

None of the above

The variation of frequency of carrier wave with respect to the amplitude of the modulating signal is called ______.

(a)

Amplitude modulation

(b)

Frequency modulation

(c)

Phase modulation

(d)

Pulse width modulation

The frequency range of 3 MHz to 30 MHz is used for ______.

(a)

Ground wave propagation

(b)

Space wave propagation

(c)

Sky wave propagation

(d)

Satellite communication

All medium wave signals received during day time use __________ wave propagation.

(a)

surface

(b)

space

(c)

sky

(d)

ionosphere

The radio waves after refraction from different part of ionosphere on reaching the earth are called as _______________.

(a)

ground wave

(b)

sky waves

(c)

space waves

(d)

micro waves

The audio frequency range is ___________.

(a)

20 Hz to 200 Hz

(b)

20 Hz to 2000 Hz

(c)

20 Hz to 200,000 Hz

(d)

20 Hz to 20,000 Hz

In AM, the amplitude of the carrier wave is changed in accordance with that of the ________ of the signal wave.

(a)

frequency

(b)

intensity

(c)

phase

(d)

time

Messages cannot be transmitted over long distances in _________ transmission.

(a)

FM

(b)

PM

(c)

AM

(d)

PCM

The change in the resting frequency of a FM transmitter is called ________

(a)

frequency swing

(b)

frequency deviation

(c)

range offrequency

(d)

centre deviation

Noise is a form of __________ variation.

(a)

time

(b)

phase

(c)

amplitude

(d)

frequency

Resistance of any photosensitive material is ______ to the intensity of light exposed

(a)

directly proportional

(b)

indirectly proportional

(c)

a constant

(d)

independent

In a television, the picture signals are _________ modulated.

(a)

amplitude

(b)

frequency

(c)

phase

(d)

pulse-code

The transmitter in a RADAR is a high power ________.

(a)

cyclotron oscillator

(b)

magnetron oscillator

(c)

Hartley oscillator

(d)

simple harmonic oscillator

The greatest technical problem with an analog communication system is _________.

(a)

noise

(b)

low speed

(c)

low range

(d)

accessibility

_________ is the most often used wire material.

(a)

Copper

(b)

Aluminium

(c)

Sulphur

(d)

iron

The principle used for 'transmission of light signals through optical fibre is ________.

(a)

refraction

(b)

diffraction

(c)

polarisation

(d)

total internal reflection

The distance of a geostationary satellite's orbit from the Earth is about _______

(a)

366 km

(b)

108 km

(c)

36 x 10³km

(d)

30 m

Mobile communication is easily established by _______ communication.

(a)

mechanical switches

(b)

telephone cables

(c)

satellite

(d)

optical fibres

In AM receiver, if 900 kHz station is tuned, then the local oscillator will have to produce a frequency of ______________.

(a)

600 kHz

(b)

455 kHz

(c)

10.7 MHz

(d)

1355 kHz

The resting frequency of the FM transmitter is 98.5MHz. The allowed minimum and maximum frequency on either side of the center frequency are respectively_____________.

(a)

98.400 MHz and 98.600 MHz

(b)

98.450 MHz and 98.550 MHz

(c)

98.425 MHz and 98.575 MHz

(d)

98.425 MHz and 98.575 MHz