Consider the optical system shown in figure. The point source of ligth S is having wavelength equal to `lambda`. The light is reaching screen only after reflection. For point P to be socond maxima, the value of `lambda` would be (`D gt gt d` and ` d gt gt lambda`)

Options

A. `(12d^(2))/(D)`
B. `(6d^(2))/(D)`
C. `(3d^(2))/(D)`
D. `(24d^(2))/(D)`

Answer

A

Explanation

At `P,Deltax=((8d)xx3d)/(D)` for `2^(nd)` maxima `Deltax=2lamdaimplies(24d^(2))/(D)=2lamda=(12d^(2))/(D)`