In an interference experiment with a biprism, the distance of the slits from the screenn is increased by 25% annd the separation between the slits is halved. If X represents the original fringe width, the new fringe width will be

Options

A. 2X
B. 1.5X
C. 2.5X
D. 4X

Answer

C

Explanation

`lamda=(Xd)/(D)" "therefore X=(lamdaD)/(d)`
`therefore X_(2)/X_(1)=(lamdaD_(2))/(d_(2))xx(d_(1))/(lamdaD_(1))`
`=((D_(2))/(D_(1)))xx((d_(1))/(d_(2)))=(5)/(4)xx(2)/(1)=(5)/(2)`
`therefore X_(2)=2.5X`