In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum with the wavelength `lambda_1` is found to be coincident with third maximum at `lambda_2`. So

Options

A. (a) `3lambda_1=0.3lambda_2`
B. (b) `3lambda_1=lambda_2`
C. (c) `lambda_1=3.5lambda_2`
D. (d) `0.3lambda_1=3lambda_2`

Answer

C

Explanation

Position of first minima=position of third maxima,
i.e., `(1xxlambda_1D)/(d)=((2xx3+1))/(2)(lambda_2D)/(d)=lambda_1=3.5lambda_2`