13 Jun 2026

Optics Exam Quiz

Five standard optics MCQs for physics entrance practice.

optics gate-2024 csir-net-2023 jest-2022

These are original exam-style practice questions based on common GATE, CSIR-NET and JEST optics patterns.

Q: [GATE 2024 style] In Young's double slit experiment, fringe width is
A: $\lambda D/d$
B: $dD/\lambda$
C: $\lambda d/D$
D: $D/(\lambda d)$
ANSWER: A
EXPLAIN: The fringe width is $\beta=\lambda D/d$.
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Q: [CSIR-NET 2023 style] Brewster's law is
A: $\tan\theta_B=n_2/n_1$
B: $\sin\theta_B=n_2/n_1$
C: $\cos\theta_B=n_1/n_2$
D: $\theta_B=0$
ANSWER: A
EXPLAIN: For light incident from medium 1 to 2, $\tan\theta_B=n_2/n_1$.
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Q: [JEST 2022 style] The Rayleigh criterion for a circular aperture gives angular resolution approximately
A: $1.22\lambda/D$
B: $D/\lambda$
C: $\lambda/2D^2$
D: $2D/\lambda$
ANSWER: A
EXPLAIN: The first diffraction minimum of a circular aperture gives $\theta\simeq1.22\lambda/D$.
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Q: [GATE 2021 style] A half-wave plate introduces phase retardation
A: $\pi/2$
B: $\pi$
C: $2\pi$
D: $0$
ANSWER: B
EXPLAIN: A half-wave plate delays one component by $\pi$ radians relative to the other.
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Q: [CSIR-NET 2020 style] For single-slit diffraction, the first minimum satisfies
A: $a\sin\theta=\lambda$
B: $a\cos\theta=\lambda$
C: $d\sin\theta=\lambda/2$
D: $a=\lambda\sin^2\theta$
ANSWER: A
EXPLAIN: Single-slit minima occur at $a\sin\theta=m\lambda$; first minimum has $m=1$.

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