Question

In Young’s double-slit experiment, the two slits are 2 mm apart. The interference fringes for light of wavelength 6000Å are formed on a screen 80 cm away from them. 

(i) How far is the second bright fringe from the central bright point? 

(ii) How far is the second dark fringe from the central bright point?

Answer 1

Data: D = 80 cm = 0.8 m,

d = 2 mm = 2 × 10^-3 m, 

λ = 6000Å = 6 × 10^-7 m

(i) For the second bright fringe from the central bright point, n = 2

This is the required distance.

(ii) For the second dark fringe from the central bright point, m = 2

This is the required distance.