JEE Main · 2021 · 27 Jul 2021 · Shift 1 · Wave Optics

In Young's double slit experiment, if the source of light changes from orange to blue then:

(A)the distance between consecutive fringes will decrease.✓ Correct
(B)the distance between consecutive fringes will increase.
(C)the central bright fringe will become a dark fringe.
(D)the intensity of the minima will increase.

Answer: (A)

Solution

The fringe width is given by

β = \frac{λ D}{d}

, which is directly proportional to wavelength

λ

. Since blue light has a shorter wavelength than orange light (

λ_{blue} < λ_{orange}

), the fringe width decreases when the source changes from orange to blue.

JEE Main · 2021 · 27 Jul 2021 · Shift 1 · Single correct option

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