In Young's double-slit experiment, the separation between the slits is halved and the distance between the slits and the screen in doubled. The fringe width is

Options

A. becomes half
B. remains the same
C. becomes six times
D. becomes four times

Answer

C

Explanation

We know the fringe width
`beta=(Dlambda)/(d) " "`…(i)
According to the question,
`rArr beta'=(D'lambda)/(d')=(3D*lambda)/(d//2)=6(Dlambda)/(d) " " `…(ii)
On dividing Eq. (ii) by Eq. (i), we get
`(beta')/(beta)=((6Dlambda)/(d))/((Dlambda)/(d))=6 rArr beta'=6beta`