Dr Sushil Kumar

Displacement of Fringes Interference Quiz

Displacement of Fringes

Last updated on Sunday, August 16th, 2020

Interference fringes with monochromatic light and white light you have read, in this quiz you will see some concept and questions if we put a thin transparent plate of any material (example: glass or mica) in the path of the two interferring waves of light.

displacement-of-fringes

Let S1 and S2 be two coherent monochromatic sources producing light of the wavelength λ. There is a thin mica (or glass) plate of thickness “t” in the path of light coming from source S1. Let “μ” be the refractive index of the plate for monochromatic light that is used in this process.

Questions are;

1. Does fringe shift depends on the time taken by the two light waves to reach at a certain point?

 
 

2. What is the relationship between refractive index “μ”, speed of light in vaccum “c”, and speed of light in any transparent medium “v”;

 
 
 
 

3. What do you think by putting a mica sheet in the path of light from S1 to P?

 

 
 
 
 

4.

When we put a mica sheet of thickness “t” in the light path it takes extra time to reach at a certain point. We know that in absence of the mica sheet, the two waves which were reaching at certain point at same time, will be different now. If that certain point shifted in that way so the light wave which is free from mica sheet reach at same time as the light with mica sheet. Then your conclusion will be;

 
 
 
 

5. The optical path travelled by the light from S1 to the P, if water is filled between source and screen, will be?

 
 
 
 

6. The time taken by light from S1 to P is

 
 
 
 

7. Let O be a center point on the screen, also distance between two slits S1 and S2 is very small. When we introduce the mica sheet in the path S1O, do you thinks that light will reach at different times at point O, compare to the path S2O.

 
 

8. We know by putting a sheet in the optical path fringes shift with a new center on screen. If we have to find effective path difference at any point (say P). The required formula will be;

 
 
 
 

9. What is the correct relation for time difference, between the two light waves which reachs at a certain point. When we put a mica sheet of thickness “t’ and refractive index “μ”, and speed of light is “c”.

 
 
 
 

10. Does time taken by the light to complete the path from S1 to P will be longer compared to the S2P. If your answer is yes, then reason of it according to you;

 

 

 

 
 
 
 

Question 1 of 10

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