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

Asked in RS Academy GUJCET booklet · Single slit diffraction

Answer: (2) the maxima and minima are narrow and more crowded

Step-by-step solution

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

Idea: for a slit of width a the minima lie at a sin θ = nλ, so every width in the pattern is proportional to the wavelength.

On a screen at distance D the fringe width is (λ D)/a.

Blue light, about 450 nm, is shorter than red, about 700 nm, so each fringe shrinks to roughly two-thirds of its former width.

The maxima and minima become narrow and more crowded.

Why the other options are wrong

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