JEE Main 2026 · 5 Apr · Shift 1 · Physics Q39

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PhysicsSingle correct+4 / -1Question 39 of 75

In Young's double slit experiment, the fringe width of the interference pattern produced on the screen is 2.4 μm. If the experiment is carried out in another medium having refractive index 1.2, the fringe width will be ________ μm.

1.2

2.4

2.88

Answer and worked solution

Official answer: B

Fringe width $\beta=\dfrac{\lambda D}d$ . In the medium, the wavelength becomes $\lambda/\mu$ :
$\beta'=\frac{2.4}{1.2}=2\ \mu\text{m}.$

(B)

Topics:Interference and Young's double slit

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JEE Main 2026 · 5 Apr · Shift 1, Physics question 39