Question

Plane wavefront of Light of wavelength 6000 Å is incident on two slits on a screen perpendicular to the direction of light rays. If the total separation of 10 brights fringes on a screen 2m away is 2 cm, find the distance between the slits.

Answer 1

Given,

Distance between 10 fringes = 2 cm = 0.02 m

λ = 6000 Å

= 6000 × 10^-10 m

∴ Fringe width,  w = `0.02/10` = 0.002 m

D = 2 m

Fringe width w = `(lambda "D")/"d"`

d = `(lambda "D")/"w"`

`= (6,000 xx 10^-10 xx 2)/0.002`

= 6 × 10^-4 m

The distance between the slits is 6 × 10^-4 m.