According to Brewster's Law, when unpolarized light is incident on a transparent medium at the polarizing angle (Brewster's angle), the reflected and refracted rays are: MCQ with Answer and Explanation

According to Brewster's Law, when unpolarized light is incident on a transparent medium at the polarizing angle (Brewster's angle), the reflected and refracted rays are:
A. At exactly 90 degrees to each other
B. At 45 degrees to each other
C. Parallel to each other
D. Totally internally reflected
Answer: Option A
Solution (By JKSSB Mock Tests)
Brewster's Law states that when light hits a dielectric boundary at a specific angle of incidence (Brewster's angle, theta_p), the reflected light is completely plane-polarized. At this exact geometric condition, the angle between the reflected ray and the refracted (transmitted) ray is strictly 90 degrees.

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Practice More Physics Questions

Question #1
The moderator used in a nuclear reactor serves to
A. Absorb neutrons
B. Cool the reactor
C. Generate neutrons
D. Slow down neutrons

Correct Answer: Option D


Explanation:
Moderator slows fast neutrons to thermal energies.

This question belongs to: Science Physics
Question #2
The power of a lens is +2 D. Its focal length is
A. 20 cm
B. 2 m
C. 50 cm
D. 0.5 m

Correct Answer: Option D


Explanation:
Power P = 1/f (in metre). f = 1/P = 1/2 = 0.5 m = 50 cm. Positive power indicates convex lens. For concave lens, power negative. Dioptre (D) is SI unit of power. Remember f in metres.

This question belongs to: Science Physics
Question #3
The critical angle for light passing from glass (n=1.5) to air is approximately:
A. 90°
B. 42°
C. 60°
D. 30°

Correct Answer: Option B


Explanation:
Critical angle θ_c for total internal reflection: sinθ_c = n₂/n₁, where n₁ > n₂. Here n₁=1.5 (glass), n₂=1 (air), so sinθ_c = 1/1.5 = 2/3 ≈ 0.6667 ⇒ θ_c = sin⁻¹(0.6667) ≈ 41.8° ≈ 42°. Memory aid: 'sinθ_c = 1/n for glass to air'. This calculation tests understanding of total internal reflection conditions, crucial for optics in competitive exams. Always ensure light travels from denser to rarer medium for TIR to be possible; otherwise, no critical angle exists.

This question belongs to: Science Physics