# Physical Optics [Optionals IAS Mains Physics]: Questions 1 - 5 of 34

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## Question 1

Physical Optics
Principles of Fibre Optics Attenuation

Appeared in Year: 2012 (IFS)

### Describe in Detail

Essay▾

A step – index silica fiber consists of core of refractive index 1.450 and diameter . If the numerical aperture of the fiber is 0.16, calculate:

(i) the acceptance angle of the fiber,

(ii) refractive index of the cladding, and

(iii) if the fiber is immersed in water of refractive index 1.33, how does the acceptance angle change? (paper -1) (Section – A)

### Explanation

• Here, from question, we can say,

• The numerical aperture of the optical fiber is given as,

• where, is acceptance angle of the fiber. is the refracting medium of surrounding of optical fiber. And are the refracting indexes of core and cladding of the optical fiber, respectively.

(i) The acceptance angle of the fiber is calculated from equation (1) as,

… (46 more words) …

## Question 2

Physical Optics
Interference of Light-Young's Experiment
Edit

Appeared in Year: 2013 (IFS)

### Describe in Detail

Essay▾

In a double slit interference experiment, show that the fringe shape is hyerbola. (Section A)

### Explanation Young՚S Double Slit Set Up
• In figure the arrangement of the Young՚s double slits experiment is shown. S is a narrow slit, from where a monochromatic light of wavelength is passing. Two other narrow slits and are there, which are far to each other of distance .
• Light waves, which come out from slit S, fall on both and , and formed two coherent sou…

… (277 more words) …

## Question 3

Physical Optics
Principles of Fibre Optics Attenuation

Appeared in Year: 2010 (IFS)

### Describe in Detail

Essay▾

With a suitable diagram, deduce an expression for numerical aperture (NA) for ab optical fiber having refractive indices of core and cladding and , respectively and being placed in a medium of index . (Section – A)

### Explanation A Light Incident in Fiber
• As shown in figure an optical fiber having refractive indices of core and cladding and , respectively. And is the refractive index of outside medium. A light beam incident at angle with core axis, and then it refracted at an angle and fall on the core – cladding interface at angle . Where,

• From Snell՚s Law, at point of e…

… (215 more words) …

## Question 4

Physical Optics
Principles of Fibre Optics Attenuation
Edit

Appeared in Year: 2010 (IFS)

### Write in Short

Short Answer▾

Between multimode and single mode fibers, explain critically how and why single mode fiber is chosen for communication. (Section – A)

## Question 5

Physical Optics
Single Mode Fibres

Appeared in Year: 2010 (IFS)

### Write in Short

Short Answer▾

Why are the two wavelengths and important in single – mode fiber – optical communication system? (Section – A)