In a biprism experiment, the distance between the two virtual images of the slit is `1.2` mm and the wavelenght of light used is 4000Å . If the distance of third bright band from central bright band is 1 mm, and the distance is and the distance between the brprism and focal palne of the eyepiece is `0.9`, then distannce between slit and biprism will be

Options

A. `0.1m `
B. `1.1 m`
C. `0.5 m`
D. `0.15`mm

Answer

A

Explanation

`x_(3b)=3beta:.beta=(1)/(3)mm`
`:.D=(d.beta)/(lamda)=(1.2xx10^(-3)xx10^(-3))/(4xx10^(-7)xx3)=1m=u+V`
`:.u=1-0.9=0.1m`