In which frequency range, space waves are normally propagated ____.
HF
VHF
UHF
SHF
If (1 and (2 are the refractive indices of the materials of core and cladding of an optical fiber, then the loss of light due to its leakage can be minimized by having ____.
(1 > (2
(1 < (2
(1 = (2
None of the above
Through which mode of propagation, the radio waves can be sent from one place to another ____.
ground wave propagation
sky wave propagation
space wave propagation
All of the above
A laser beam of pulse power 1012 watt is focused on an object are 10–4 cm2. The energy flux in watt/ cm2 at the point of focus is ____.
1020
1016
108
104
The carrier frequency generated by a tank circuit containing 1 n F capacitor and 10 (H inductor is ____.
1592 Hz
1592 MHz
1592 kHz
159.2 Hz
Broadcasting antennas are generally ____.
omni directional type
vertical type
horizontal type
None of the above
For television broadcasting, the frequency employed is normally ____.
30-300 MHz
30-300 GHz
30-300 KHz
30-300 Hz
The radio waves of frequency 300 MHz to 3000 MHz belong to ____.
high frequency band
very high frequency band
ultra high frequency band
super high frequency band
Maximum useable frequency (MUF) in F-region layer is x, when the critical frequency is 60 MHz and the angle of incidence is 70°. Then x is ____.
150 MHz
170 MHz
175 MHz
190 MHz
The electromagnetic waves of frequency 2 MHz to 30 MHz are ____.
in ground wave propagation
in sky wave propagation
in microwave propagation
in satellite communication
A laser is a coherent source because it contains ____.
many wavelengths
uncoordinated wave of a particular wavelength
coordinated wave of many wavelengths
coordinated waves of a particular wavelength
The attenuation in optical fiber is mainly due to ____.
absorption
scattering
neither absorption nor scattering
Both A and B
The maximum distance upto which TV transmission from a TV tower of height h can be received is proportional to ____.
h1/2
h
h3/2
h2
A laser beam is used for carrying out surgery because it ____.
is highly monochromatic
is highly coherent
is highly directional
can be sharply focused
Laser beams are used to measure long distances because ____.
they are monochromatic
they are highly polarized
they are coherent
they have high degree of parallelism
An oscillator is producing FM waves of frequency 2 kHz with a variation of 10 kHz. What is the modulating index ?
0.20
5.0
0.67
1.5
The maximum peak to peak voltage of an AM wire is 24 mV and the minimum peak to peak voltage is 8 mV. The modulation factor is ____.
10%
20%
25%
50%
Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50 V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper side-band frequencies in kHz are ____.
1490, 1510
1510, 1490
What is the modulation index of an over modulated wave?
1
Zero
<1
>1
Basically, the product modulator is____.
an amplifier
a mixer
a frequency separator
a phase separator
If fa and ff represent the carrier wave frequencies for amplitude and frequency modulations respectively, then ____.