Q.1.
A T.V. tower has a height 200 m. By how much the height of tower be increased totriple its coverage range ?
-
33%
a)1600 m
-
17%
b)800 m
-
17%
c)1800 m
-
33%
d)600 m
Q.2.
The transmission of audio signal in radio broadcasting is type.
-
29%
a) ASK
-
14%
b) FSK
-
14%
c) AM
-
43%
d) FM
Q.3.
Transmission loss per km in the optical fibre,used presently is,
-
33%
a)20 dB
-
33%
b) 2 dB
-
17%
c)0.2 dB
-
17%
d)0.02 dB
Q.4.
In satellite communication 6 GHz frequency is used for and 4 GHz frequencyis used for
-
0%
a)uplink, down link
-
50%
b)down link, up link
-
50%
c)modulation, demodulation
-
0%
d)demodulation, modulation
Q.5.
If a radio receiver amplifier all the signal frequencies equally well, it is said to have high
-
0%
a) fidelity
-
25%
b)distortion
-
50%
c)sensibility
-
25%
d) sensitivity
Q.6.
In frequency modulation
-
33%
a) the amplitude of modulated wave varies as frequency of carrier wave.
-
67%
b) the frequency of modulated wave varies as amplitude of modulating wave.
-
0%
c) The amplitude of modulated wave varies as amplitude of carrier wave.
-
0%
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
-
67%
a)remain constant
-
33%
b) appears to decrease
-
0%
c)appears to increase
-
0%
d)changes randomly
Q.8.
For 100% modulation, What is the value of minimum amplitude Emin of the modulatedwave ?
-
50%
a)Zero
-
0%
b)1
-
50%
c)2
-
0%
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 ?
-
0%
a)1.2
-
50%
b)1.44
-
0%
c)0.69
-
50%
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]
-
0%
a) The frequency of the microwaves must match the resonant frequency of the water molecules
-
50%
b) The frequency of the microwaves has no relation with natural frequency of water molecules
-
50%
c) Microwaves are heat waves, so always produce heating
-
0%
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]
-
0%
a) 1.20 × 10–6 N
-
0%
b) 3.0 × 10–6 N
-
100%
c) 1.25 × 10–6 N
-
0%
d) 2.50 × 10–6 N
Explanation
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]
-
0%
a) E/C2
-
50%
b) E/C
-
50%
c) 2E/C
-
0%
d) 2E/C2
Q.13.
Out of the following options which one can be used to produce a propagating electromagnetic wave ?
-
50%
a) A charge moving at constant velocity
-
0%
b) A stationary charge
-
50%
c) A charge less particle
-
0%
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
-
50%
a) 1.41 × 10–8 T
-
0%
b) 2.83 × 10–8 T
-
50%
c) 0.70 × 10–8 T
-
0%
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]
-
50%
a) 10.62 MHz
-
0%
b) 10.62 kHz
-
50%
c) 5.31 MHz
-
0%
d) 5.31 kHz
Explanation
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]
-
0%
a) 3 V/m
-
0%
b) 6 V/m
-
100%
c) 9 V/m
-
0%
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
-
50%
a) 0.3 × 10−17 kg ms−1
-
0%
b) 1.0 × 10−17 kg ms−1
-
50%
c) 3.0 × 10−17 kg ms−1
-
0%
d) 9.0 × 10−17 kg ms−1
Explanation
