Physical Optics [IFS (Forest Services) Physics]: Questions 6 - 10 of 47

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Question 6

Appeared in Year: 2013

Describe in Detail Subjective▾

Explain the lasing action of laser using energy level diagram and describe the operation of laser experimental setup. (Section A)

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Explanation

  • The light is produced in He – Ne laser by atomic transitions in the Neon atom. The Helium acts as a buffer gas in it. That means Helium doesn՚t directly produce laser light, it only helps the atom of the Neon gas to produce lasing in as manner.
  • Helium absorbed some energy, when energy applied to the He – Ne gas mixture, and it achieve an excited sta…

… (457 more words, 8 figures) …

Question 7

Appeared in Year: 2002 (IAS)

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A wave is represented by Find wavelength , velocity , Frequency and the direction of propagation. If it interferes with another wave given by find the amplitude and the phase of the resultant wave. (20 Marks)

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Explanation

… (289 more equations) …

Question 8

Appeared in Year: 1999 (IAS)

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What are the essential conditions for observing the interference of light? Two coherent sources with intensity ratio interfere. Find (20 Marks)

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Explanation

It is not always necessary that two superimposing light waves always interfere and result in the redistribution of energy (fringes) . Only where these superimposing waves satisfy certain conditions the fringe pattern is observed on screen. These conditions are as follows:

  1. The phase difference between the two waves should not change with time. If the…

… (224 more words) …

Question 9

Appeared in Year: 2010 (IAS)

Write in Short Short Answer▾

What should be the refractive index of cladding of an optical fibre with numerical aperture with refractive index of core as ? (10 Marks)

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Question 10

Appeared in Year: 2007 (IAS)

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The radius of the first zone in a zone plate is . What will be the position of the first image of a point source of light of light of wavelength placed at a distance of from the zone plate.

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Explanation

For , the radius of the zone, the relation can be written as

is the distance of the source from the zone plate and is the distance of screen from th…

… (154 more equations) …