Question

Two slits 0.125 mm apart are illuminated by light of wavelength 4500 Å. The screen is 1 m away, bright fringe on both sides of the central maximum. 

The ratio of intensities of minima to maxima in YDSE is 9 : 25. Find the ratio of width of two slits.

Answer 1

Here, d = 0.125 mm = 0.125 x 10^-3 m,

λ = 4500 Å = 4500 x 10^-10 m = 4.5 x 10^-7 m,

D = 2 m, n = 2

If x is distance of 2^nd bright fringe on each side, then separation between them