Question

In Young’s double-slit experiment, interference fringes are observed on a screen 1 m away from the two slits which are 2 mm apart. A point P on the screen is 1.8 mm from the central bright fringe,

(i) Find the path difference at P. 

(ii) If the wavelength of the light used in 4800 Å, what can you say about the illumination at P?

Answer 1

Data : D = 1 m, 

d = 2 mm = 2 × 10^-3 m, 

y = 1.8 mm = 1.8 × 10^-3 m, 

λ = 4800 Å = 4.8 × 10^-7 m

As the path difference is an odd integral multiple of \(\cfrac λ2\).

point P is a dark point with minimum intensity.