A parallel beam of monochromatic light falls normally on a single narrow slit. The angular width of the central maximum in the resulting diffraction pattern (a) increases with increase of slit width. (b) decreases with increase of slit width. (c) decreases with decrease of slit width. (d) may increase or decrease with decrease of slit width.

Answer: (b). Angular width of central maximum = (2λ)/(a), so it is inversely proportional to slit width a. Wider slit gives a narrower central maximum. So the answer is (b) decreases with increase of slit width.

A parallel beam of monochromatic light falls normally on a single… | MHT CET 2023 (10 May, Shift 2)

Q45MHT CET 2023 · 10 MAY · SHIFT 2Easy

Diffraction at a Single Slit

A parallel beam of monochromatic light falls normally on a single narrow slit. The angular width of the central maximum in the resulting diffraction pattern

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Answer: (b)

Angular width of central maximum $= \dfrac{2\lambda}{a}$ , so it is inversely proportional to slit width $a$ .
Wider slit gives a narrower central maximum.
So the answer is (b) decreases with increase of slit width.

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