Question

what is the path difference between 2 light waves, forming the 5th fringe on a screen?​

Answer 1

Answer:

If path difference between 2 waves is integral multiple of wavelength, which satisfies condition for constructive interference. Whereas, if path difference between 2 waves is odd integral multiple of half wavelength, it satisfies condition for destructive.

Answer 2

Answer:

Explanation:

Given,

path difference (△)=13.5λ.....(i)

We know that,

path difference (△)=(n+  

2

1

​  

)λ.....(ii)

We can write Eq. (i) in the following form

△=(13+  

2

1

​  

)λ.....(iii)

From Eqs. (ii) and (iii), it is clear that there will be minima. So, the point will be dark.