For efficient transmission of a 100 MHz frequency wave, the minimum length of an antenna should be
1) 3 m 2) (¾) m 3) 10 m 4) 100 m Answer: 2) (¾) m Solution: Height of the antenna... View Article
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Suppose the amplitude of a modulated wave is equal to the signal amplitude. Then modulation is
1) 10% 2) 25% 3) 50% 4) 100% Answer: 4) 100% Solution: If the amplitude of a modulated wave is equal... View Article
Which of the following is related to telecommunication?
1) X-rays 2) r-rays 3) Sound wave 4) Microwaves Answer: 4) Microwaves Solution: Microwaves is used in telecommunication
For an amplitude modulated wave, the maximum amplitude is found to be 9V while the minimum amplitude is found to be 3V. The modulation index is____________
1) 100% 2) 75% 3) 50% 4) 25% Answer:50 % Solution: μ = [(Vmax – Vmin)/(Vmax + Vmin)] x 100... View Article
Device that transforms one form of energy into another form of energy is called a ___________
1) Transducer 2) Transformer 3) Transponder 4) Transistor Answer: 1) Transducer Solution: The transducer is a device or an arrangement that... View Article
Which of the following is not a component of a communication system
1) Transmitter 2) Transmission channel 3) Noise 4) Receiver Answer: 3) Noise Solution: The communication system consists of three basic components:... View Article
In light modulation, which characteristic of the carrier light wave is varied?
1) Amplitude 2) Frequency 3) Phase 4) Intensity Answer:4) Intensity Solution: In light modulation intensity of the carrier light wave... View Article
Intensity of electric field of ground waves is ____________of the distance travelled by it
1) Square 2) Inverse of root 3) Proportion 4) Inverse Answer: 4) Inverse Solution: The intensity of the electric field of... View Article
The bandwidth of the audio signal is
1) 20 Hz 2) 20 kHz 3) 20 MHz 4) 20 GHz Answer: 2) 20 kHz Solution: The bandwidth of the... View Article
The advantage of optical fibre is
1) high bandwidth and EM interference 2) low bandwidth and EM interference 3) high bandwidth, low transmission capacity and no... View Article
Which one of the following is an incorrect statement in the transmission of electromagnetic waves
1) Ground wave propagation is for high-frequency transmission 2) Skywave propagation is facilitated by ionospheric layers 3) Space wave is... View Article
For a body moving with relativistic speed, if the velocity is doubled, then
1) its linear momentum is doubled 2) its linear momentum will be less than double 3) its linear momentum will... View Article
Two electrons are moving in an opposite direction with speeds of 0.8 c and 0.4 c, where c is the speed of light in a vacuum. Then, the relative speed is about
1) 0.4 c 2) 0.8 c 3) 0.9 c 4) 1.2 c Answer: 3) 0.9 c Solution: Relativity addition formula, \(\begin{array}{l}v_{rel}=... View Article
A laser device produces amplification in the
1) microwave region 2) ultraviolet or visible region 3) infrared region 4) None of the above Answer: 2) ultraviolet or visible... View Article
In a ruby laser, the stimulated emission is due to the transition from
1) metastable state to any lower state 2) any higher state to lower state 3) metastable state to ground state... View Article
Which of the following is not the main characteristic of laser beam?
1) Highly intense 2) Highly directional 3) Highly monochromatic 4) incoherent Answer: 4) incoherent Solution: The laser light is 1) Highly... View Article
A laser beam is used for carrying out surgery because it
1) is highly monochromatic 2) is highly coherent 3) is highly directional 4) can be sharply focused Answer: 4) can be... View Article
If the area to be covered for TV telecast is doubled, then the height of the transmitting antenna (TV tower) will have to be
1) doubled 2) halved 3) quadrupled 4) kept unchanged Answer: 1) doubled Solution: The is given by d = √2Rh h ∝ d2 ∝... View Article
The waves relevant to telecommunication are
1) visible light
2) infrared
3) ultraviolet
4) microwave
5) None of the above
Answer: 4) microwave Solution: Microwaves are used in telecommunication since their frequency is high enough to carry the information. The microwaves... View Article
In coaxial cable the material used as space is
1) teflon (or) polyethylene 2) glass or mica 3) a gaseous medium 4) glass 5) mica Answer: 1) Teflon (or) polyethylene... View Article
