in a two-slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is moved by `5xx10^(-2)` m towards the slits, the change in fringe width is `3xx10^(-5)`. If the distance between the slits is `10^(-3)`m, calculate the wavelength of the light used.

Options

A. 4500 Å
B. 3000 Å
C. 5000 Å
D. 6000 Å

Answer

D

Explanation

As, `beta=(lambdaD)/(d) and beta'=(lambdaD')/(d)`
`therefore beta-beta'=(lambda(D-D'))/(d)`
`rArr 3xx10^(-5)=(lambda xx5xx10^(-2))/(10^(-3))`
Wavelength of light
`lambda=(3xx10^(-6))/(50)=6xx10^(-7)m=6000` Å