Consider the optical system shown in Fig. The point source of light S is having wavelength equal to λ . The light is reaching screen only after reflection. For point P to besecond maxima, the value of λ would be (D > >

Correct answer: A. 12 d^ 2 D At P, Δ x= (8 d) × 3 d D For 2 nd maxima, Δ x=2 λ array l 24 d^ 2 D =2 λ λ= 12 d^ 2 D array

BITSAT 2021

BITSAT 2021 · Physics · Wave Optics

Consider the optical system shown in Fig. The point source of light...

Consider the optical system shown in Fig. The point source of light

S

is having wavelength equal to

\lambda

. The light is reaching screen only after reflection. For point

P

to besecond maxima, the value of

\lambda

would be

(\mathrm{D} > > d

and

d > > \lambda)

A. $\frac{12 d^{2}}{\mathrm{D}}$

\text{ At } \mathrm{P}, \Delta x=\frac{(8 d) \times 3 d}{\mathrm{D}}

For 2 nd maxima,

\Delta x=2 \lambda

\begin{array}{l} \Rightarrow \frac{24 d^{2}}{\mathrm{D}}=2 \lambda \\ \Rightarrow \lambda=\frac{12 d^{2}}{\mathrm{D}} \end{array}