In a Young’s double slit experiment, the slit separation is `0.2 cm`, the distance between the screen and slit is 1 m . Wavelength of the light used is `5000 Å`. The distance between two consecutive dark fringes (in mm ) is

Options

A. `2 xx 10^(-5)m`
B. `2 xx 10^(-3)m`
C. `0.2 xx 10^(-3)m`
D. None of these

Answer

D

Explanation

Fringe width
`beta = (lambda D)/(d)`
Given : `lambda = 1000 Å = 10^(-5) cm, d = 3 cm, D = 70 cm`
Putting given value in eq (i)
`therefore beta = (10^(-5) xx 70)/(3) = 23.3 xx 10^(-5)cm = 2.3 xx 10^(-6)m`