Question

in young's double slit experiment, fourth bright fringe is formed at a distance x from central fringe. The distance between it and second dark fringe on the same side of central maxima is?​

Answer 1

Answer: 3x/8

Explanation:

Distance from Central Bright Fringe(CBF) ( fourth) is x

(And we know that this distance is equal to y= n lamda D/d)

Therefore, x= 4 lambda D/d

Or we can say, lamda D/d = x/4

Now next part. For Dark fringe from CBF

x’ = (2n-1) lamda D/2d , and according through question x’= (2*2-1) lamba D/2d

x’= 3 lambdaD/2d

And from above lamda D/d = x/4

Therefore x’= 3/2* x/4

And we get the answer, X’ = 3x/8