GATE (Graduate Aptitude Test in Engineering) Electronics: Questions 768 - 771 of 1076

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Passage

Optical fibre communication is one among the new techniques have come up and are extensively used for communication purposes. The portion of the e. m. spectrum encompasses the optical region falls in the wavelength of 50 nm (Ultraviolet) to approximately 100 µm (Infrared) which includes visible light spectrum from 400 nm (Violet) to 700 nm (Red) . The order of frequency corresponding to these wavelengths falls in the range to Hz. There are two types of transmission media used for optical communication i.e.. , atmospheric channel and guided wave channel. Out of the two, guided wave channel provide much more reliable and versatile medium of communication. The medium used for guided channels in optical range are non-metallic guides popularly known as optical fibre. The optical fibre link used for communication applications has several advantages over conventional cupper cable links which makes possible to send much more data over long distances with negligible attenuation. Although some difficulties do exist in the making of optical fibre set and there are some challenges being faced yet this type of communication mechanism has made a great impact in the present scenario.

Question 768 (1 of 4 Based on Passage)

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

The following are correct about a semiconductor LASER: (December)

1. It requires population inversion

2. It has shorter lifetime than LED

3. It demonstrates spontaneous emission phenomenon

4. It generates monochromatic incoherent light.

Find out the correct answer:

Choices

Choice (4)Response

a.

1 & 2

b.

2 & 4

c.

1 & 4

d.

1 & 3

Question 769 (2 of 4 Based on Passage)

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

When atoms in Direct bandgap semiconductors move from higher energy state () to lower energy state () and emission of light takes place, the energy of emitted photon is given as (December)

Choices

Choice (4)Response

a.

b.

c.

d.

Question 770 (3 of 4 Based on Passage)

Circuits for Analog Communications

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

Following is not the usual classification of an optical fibre: (December)

Choices

Choice (4)Response

a.

Multimode step index

b.

Single mode step index

c.

Multimode graded index

d.

Single mode graded index

Question 771 (4 of 4 Based on Passage)

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

A multimode step-index fibre has glass core () and fused quartz cladding () , which one of the following is the value of acceptance angle?

(December)

Choices

Choice (4)Response

a.

b.

c.

d.

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