NEET Physics: Laws of reflection and refraction Practice Questions
13 free multiple-choice questions on Laws of reflection and refraction (Wave Optics) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. The angle of incidence is defined as the angle between the incident ray and the normal at the point of incidence. Which of the following statements is true regarding the reflection of light?
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Correct answer: D — The angle of incidence is always equal to the angle of reflection.
According to the Law of Reflection, the angle of incidence (i) is always equal to the angle of reflection (r), measured with respect to the normal to the surface of incidence.
Q2. If the speed of light in a medium is v₁ and the speed of light in another medium is v₂, and light enters the second medium, the relationship described by Snell's Law relates these speeds to the angles of incidence and refraction. Which statement accurately describes the relationship?
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Correct answer: B — The ratio of the sines of the angles is equal to the ratio of the speeds.
Snell's Law is mathematically expressed as n₁ sin i₁ = n₂ sin r₂, where n is the refractive index (n = c/v). Since n = 1/v (if c is constant), the relationship involves the ratio of the sines of the angles being proportional to the ratio of the refractive indices, which depends on the ratio of speeds.
Q3. The refractive index of a medium is defined as the ratio of the speed of light in vacuum to the speed of light in that medium. This definition relates to which phenomenon?
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Correct answer: C — Refraction of light
The refractive index (n) is fundamentally derived from the ratio of the speed of light in vacuum (c) and the speed of light in the specific medium (v), i.e., n = c/v.
Q4. The law of reflection states that the angle of incidence is equal to the angle of reflection. If a ray of light strikes a surface making an angle of 30° with the normal, what is the angle of reflection?
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Correct answer: D — 30°
According to the law of reflection, the angle of incidence is equal to the angle of reflection. If the angle of incidence is 30°, the angle of reflection must also be 30°.
Q5. What is the refractive index of a medium?
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Correct answer: C — The ratio of the speed of light in vacuum to the speed of light in the medium
The refractive index (n) of a medium is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in that medium (v): n = c/v.
Q6. If a light ray travels from a rarer medium into a denser medium, what happens to the angle of refraction compared to the angle of incidence?
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Correct answer: C — The angle of refraction is smaller than the angle of incidence
When light travels from a rarer medium to a denser medium, it bends towards the normal. Therefore, the angle of refraction is smaller than the angle of incidence.
Q7. When light travels from a medium of lower optical density (rarer medium) to a medium of higher optical density (denser medium), what happens to the angle of refraction?
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Correct answer: D — The angle of refraction decreases
When light travels from a rarer medium to a denser medium, the speed of light decreases, causing the refracted ray to bend towards the normal. Therefore, the angle of refraction decreases.
Q8. The phenomenon where light is completely reflected back into the denser medium because the angle of incidence exceeds a critical value is known as:
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Correct answer: D — Total Internal Reflection
Total Internal Reflection (TIR) occurs when light traveling in a denser medium strikes the boundary with a rarer medium at an angle greater than the critical angle.
Q9. If the angle of incidence of a ray of light is 30°, what is the angle of reflection?
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Correct answer: D — 30°
According to the Law of Reflection, the angle of incidence is equal to the angle of reflection. Therefore, if the angle of incidence is 30°, the angle of reflection is also 30°.
Q10. When light travels from a rarer medium to a denser medium, the refracted ray bends:
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Correct answer: C — Towards the normal
When light enters a denser medium, it bends towards the normal.
Q11. When light strikes a boundary between two media, the angle of incidence is defined relative to which line?
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Correct answer: A — The normal to the surface
The angle of incidence is always measured with respect to the normal (the line perpendicular) to the surface at the point where the light strikes.
Q12. If a light ray strikes a plane surface, the reflected ray and the incident ray always lie in which plane?
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Correct answer: C — The plane of reflection
The incident ray, the reflected ray, and the normal drawn at the point of incidence all lie in the same plane, which is the plane of reflection.
Q13. According to the law of reflection, the angle of incidence is always equal to the:
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Correct answer: B — Angle of reflection
The first law of reflection states that the angle of incidence (θᵢ) is equal to the angle of reflection (θᵣ).
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