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.

Answer

6000Å

Explanation

Fringe width `beta=(lamdaD)/(d),beta'=(lamda(D-5xx10^(-2)))/(d)`
Given `|beta'-beta|=|(lamda(D-5xx10^(-2)))/(d)-(lamdaD)/(d)|`
`therefore3xx10^(-5)=(lamdaxx5xx10^(-2))/(d)`
`thereforelamda=(3xx10^(-5)xx10^(-3))/(5xx10^(-2))=6000Å`