Q 12-10-020NEETJEE MainMedium
Light of wavelength $500$ nm falls on a slit $0.2$ mm wide. The width of the central maximum on a screen $1$ m away is
Answer: (A) $5$ mm
Concept. Width of the central maximum $= \dfrac{2\lambda D}{a}$.
Step 1. Substitute.
$$\frac{2 \times 500 \times 10^{-9} \times 1}{0.2 \times 10^{-3}} = 5 \times 10^{-3}\ \text{m} = 5\ \text{mm}$$
Answer. $5$ mm (Option A).
Solution by Sreeraj P, M.Sc Physics