71 questions across 1 question group — pick any mix to generate a Physics paper with step-by-step answer keys.
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
If a number of sine waves with modulation indices n1, n2, n3 ........ modulate a carrier wave, then total modulation index (n) of the wave is
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(a) n1 + n2 .... + 2(n1 + n2.....) |
(b) |
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(c) |
(d) None of these |
If fa and ff represent the carrier wave frequencies for amplitude and frequency modulations respectively, then
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(a) |
(b) |
(c) |
(d) |
For sky wave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
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(a) ~ 1.2 × 1012 m–3 |
(b) ~ 106 m–3 |
(c) ~ 1014 m–3 |
(d) ~ 1022 m–3 |
Consider telecommunication through optical fibres. Which of the following statements is not true
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(a) Optical fibres may have homogeneous core with a suitable cladding |
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(b) Optical fibres can be of graded refractive index |
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(c) Optical fibres are subject to electromagnetic interference from outside |
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(d) Optical fibres have extremely low transmission loss |
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
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(a) 1490, 1510 |
(b) 1510, 1490 |
(c) |
(d) |
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