Communication System (AIIMS Physics): Questions 1 - 5 of 12

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Question number: 1

» Communication System » Sky and Space Wave Propagation

Appeared in Year: 2005

MCQ▾

Question

For sky wave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere –

Choices

Choice (4) Response

a.

1022m3

b.

1.2×1012m3

c.

106m3

d.

1014m3

Question number: 2

» Communication System » Amplitude and Frequency Modulation

Appeared in Year: 2006

MCQ▾

Question

Given below is a circuit diagram of an AM demodulator

Circuit diagram of an AM demodulator

Circuit Diagram of an AM Demodulator

In figure circuit of an AM demodulator is shown. In which R and C parallel connected.

For good demodulation of AM signal of carrier frequency f, the value of RC should be –

Choices

Choice (4) Response

a.

RC<1f

b.

RC1f

c.

RC=1f

d.

RC1f

Question number: 3

» Communication System » Propagation of Electromagnetic Waves in the Atmosphere

Appeared in Year: 2003

MCQ▾

Question

The maximum distance up to which TV transmission from a TV tower of height h can be received is proportional to –

Choices

Choice (4) Response

a.

h12

b.

h2

c.

h32

d.

h

Question number: 4

» Communication System » Sky and Space Wave Propagation

Appeared in Year: 2003

MCQ▾

Question

In short wave communication waves of which of the following frequencies will be reflected back by the ionosphere layer having electron density 1011 per m3?

Choices

Choice (4) Response

a.

2 MHz

b.

12 MHz

c.

10 MHz

d.

18 MHz

Question number: 5

» Communication System » Propagation of Electromagnetic Waves in the Atmosphere

Appeared in Year: 2006

Assertion-Reason▾

Assertion (Ꭺ)

Electromagnetic waves with frequencies smaller than the critical frequency of ionosphere cannot be used for communication using sky wave propagation.

Reason (Ꭱ)

The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.

Choices

Choice (4) Response

a.

Both Ꭺ and Ꭱ are false

b.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

c.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

d.

Ꭺ is true but Ꭱ is false

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