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A diffraction pattern is formed by blue light. If the blue light is replaced by yellow light, then ________.

Asked in GUJCET 2016 · Single slit diffraction

Answer: (3) the maxima and minima are broadened and become distinct

Step-by-step solution

Given: a diffraction pattern first in blue light and then in yellow light.

Idea: for a slit of width a the minima lie at a sin θ = nλ, so every angle in the pattern scales with the wavelength.

On a screen at distance D the central maximum is (2λ D)/a wide and the later fringes are (λ D)/a apart.

Yellow light, about 580 nm, has a longer wavelength than blue, about 450 nm, so every fringe grows by roughly a third.

The maxima and minima are broadened and become more distinct.

Why the other options are wrong

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