Q.1
A T.V. tower has a height 200 m. By how much the height of tower be increased totriple its coverage range ?
  • a)1600 m
  • b)800 m
  • c)1800 m
  • d)600 m
Q.2
The transmission of audio signal in radio broadcasting is type.
  • a) ASK
  • b) FSK
  • c) AM
  • d) FM
Q.3
Transmission loss per km in the optical fibre,used presently is,
  • a)20 dB
  • b) 2 dB
  • c)0.2 dB
  • d)0.02 dB
Q.4
In satellite communication 6 GHz frequency is used for and 4 GHz frequencyis used for
  • a)uplink, down link
  • b)down link, up link
  • c)modulation, demodulation
  • d)demodulation, modulation
Q.5
If a radio receiver amplifier all the signal frequencies equally well, it is said to have high
  • a) fidelity
  • b)distortion
  • c)sensibility
  • d) sensitivity
Q.6
In frequency modulation
  • a) the amplitude of modulated wave varies as frequency of carrier wave.
  • b) the frequency of modulated wave varies as amplitude of modulating wave.
  • c) The amplitude of modulated wave varies as amplitude of carrier wave.
  • d) The frequency of modulated wave varies as frequency of modulating wave.
Q.7
When electromagnetic waves enter the ionized layer of ionosphere, the relative permittingof the ionized layer
  • a)remain constant
  • b) appears to decrease
  • c)appears to increase
  • d)changes randomly
Q.8
For 100% modulation, What is the value of minimum amplitude Emin of the modulatedwave ?
  • a)Zero
  • b)1
  • c)2
  • d)3
Q.9
The velocity of e.m. waves in a medium is 2.5×108 m/s . what is the dielectric constantof the medium ?
  • a)1.2
  • b)1.44
  • c)0.69
  • d)1.6
Q.10
The condition under which a microwave oven heats up a food item containing water molecules most efficiently is … [ NEET 2013]
  • a) The frequency of the microwaves must match the resonant frequency of the water molecules
  • b) The frequency of the microwaves has no relation with natural frequency of water molecules
  • c) Microwaves are heat waves, so always produce heating
  • d) Infra-red waves produce heating in a microwave oven
Q.11
Light with an energy flux of 25 × 104Wm–2 falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm2, the average force exerted on the surface is … [AIPMT 2014]
  • a) 1.20 × 10–6 N
  • b) 3.0 × 10–6 N
  • c) 1.25 × 10–6 N
  • d) 2.50 × 10–6 N
Q.12
A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C = Velocity of light) …[ NEET 2015]
  • a) E/C2
  • b) E/C
  • c) 2E/C
  • d) 2E/C2
Q.13
Out of the following options which one can be used to produce a propagating electromagnetic wave ?
  • a) A charge moving at constant velocity
  • b) A stationary charge
  • c) A charge less particle
  • d) An accelerating charge
Q.14
In an electromagnetic wave in free space the root mean square value of the electric field is Erms= 6 V/m. The peak value of the magnetic field is
  • a) 1.41 × 10–8 T
  • b) 2.83 × 10–8 T
  • c) 0.70 × 10–8 T
  • d) 4.23 × 10–8 T
Q.15
A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it. … [ IIT main 2013]
  • a) 10.62 MHz
  • b) 10.62 kHz
  • c) 5.31 MHz
  • d) 5.31 kHz
Q.16
The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is …[ IIT Mains 2013]
  • a) 3 V/m
  • b) 6 V/m
  • c) 9 V/m
  • d) 12 V/m
Q.17
A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30 mW and the speed of light is 3 × 108 ms−The final momentum of the object is
  • a) 0.3 × 10−17 kg ms−1
  • b) 1.0 × 10−17 kg ms−1
  • c) 3.0 × 10−17 kg ms−1
  • d) 9.0 × 10−17 kg ms−1
0 h : 0 m : 1 s