NEET (UG)

Practice Test 1 — Wave Optics

12 questions • 18 minutes • auto-graded with full solutions
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Section A — MCQ (Single Correct)
Question 1

A wavefront is a surface of constant:

Solution: Constant phase defines a wavefront.
Question 2

The fringe width in Young's double-slit experiment is:

Solution: $\beta = \lambda D/d$.
Question 3

Two sources must be ___ to produce a stable interference pattern.

Solution: Coherence is essential.
Question 4

In single-slit diffraction, the minima occur at:

Solution: $a\sin\theta = n\lambda$.
Question 5

The central maximum of a single-slit pattern is:

Solution: Widest and brightest band.
Question 6

Malus's law gives the transmitted intensity as:

Solution: $I = I_0\cos^2\theta$.
Question 7

Brewster's angle is given by:

Solution: $\tan\theta_B = n$.
Question 8

Polarisation is possible only for:

Solution: Only transverse waves can be polarised.
Section B — Assertion & Reason
Question 9

A: Two independent light bulbs cannot produce a sustained interference pattern.
R: Interference requires two coherent sources with a constant phase difference.

Solution: Independent bulbs lack coherence, so no stable pattern — R explains A.
Question 10

A: When the double-slit apparatus is immersed in water, the fringe width decreases.
R: The wavelength of light decreases in a denser medium.

Solution: Smaller $\lambda$ in water gives smaller $\beta = \lambda D/d$ — R explains A.
Question 11

A: Sound waves can be polarised just like light waves.
R: Polarisation is a property exhibited only by transverse waves.

Solution: Sound is longitudinal and cannot be polarised, so A is false; R correctly states only transverse waves polarise.
Question 12

A: A telescope with a larger objective can resolve finer detail.
R: A larger aperture reduces diffraction spreading, improving resolving power.

Solution: Less diffraction at a larger aperture means better resolution — R explains A.