Problem

In YDSE, if a bichromatic light having wavelengths

\lambda_1

and

\lambda_2

is used, then the maxima due to both lights will overlap at a certain distance

y

from the central maxima. Take separation between slits as

d

and distance between screen and slits as

D

. Then the value of

y

will be (1)

\left(\frac{\lambda_1 + \lambda_2}{2D}\right)d

(2)

\left(\frac{\lambda_1 - \lambda_2}{D}\right)2d

(3) LCM of

\frac{\lambda_1 D}{d}

and

\frac{\lambda_2 D}{d}

(4) HCF of

\frac{\lambda_1 D}{d}

and

\frac{\lambda_2 D}{d}