Chapter Exam

Chapter-11 Light — Online MCQ Test

Q: What is the angle between the incident ray and the reflected ray when light reflects off a plane mirror at an angle of incidence of 30°?

Answer: D. 120° — The angle of reflection equals the angle of incidence (30°). The angle between incident and reflected rays is 2 × angle of incidence = 2 × 30° = 60°. Wait, reconsidering: incident ray comes in at 30° to normal, reflects at 30° to normal on opposite side, making total angle = 180° - 60° = 120°.

Q: Which of the following is NOT a characteristic of a real image formed by a concave lens?

Answer: D. Always real and inverted — Concave lenses always form virtual, erect, and diminished images. They never form real images, so 'always real and inverted' is incorrect.

Q: A convex lens of focal length 5 cm is used as a magnifying glass. An object is placed 3 cm from the lens. What can be concluded about the image formed?

Answer: C. Virtual, erect, and magnified (magnification > 5) — When object is placed between focus and lens (u < f), using lens formula with u = 3 cm and f = 5 cm gives negative v (virtual image on same side). Magnification m = -v/u is greater than 1, erect, and magnified.

Q: Which of the following statements about critical angle and total internal reflection is INCORRECT?

Answer: C. For angles greater than critical angle, some light is refracted out of the medium — For angles greater than the critical angle, NO light is refracted out—only total internal reflection occurs. Light does not refract beyond the critical angle.

PHYSICS · Grade 10 · IGCSE cambridge

Practice Chapter-11 Light with a free chapter-wise online MCQ test for IGCSE cambridge Grade 10 PHYSICS. This chapter covers: Reflection and refraction of light lenses ray diagrams and dispersion of white light.. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-11 Light — Important Questions & Answers (FAQ)

Frequently asked questions from IGCSE cambridge Grade 10 PHYSICS — Chapter-11 Light, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is the angle between the incident ray and the reflected ray when light reflects off a plane mirror at an angle of incidence of 30°?

A. 30°
B. 60°
C. 90°
D. 120° ✓

Answer: D. 120°
The angle of reflection equals the angle of incidence (30°). The angle between incident and reflected rays is 2 × angle of incidence = 2 × 30° = 60°. Wait, reconsidering: incident ray comes in at 30° to normal, reflects at 30° to normal on opposite side, making total angle = 180° - 60° = 120°.

Which of the following is NOT a characteristic of a real image formed by a concave lens?

A. Always virtual
B. Always erect
C. Always diminished
D. Always real and inverted ✓

Answer: D. Always real and inverted
Concave lenses always form virtual, erect, and diminished images. They never form real images, so 'always real and inverted' is incorrect.

A student places an object 15 cm from a convex lens of focal length 10 cm. Where will the image be formed?

A. 30 cm on the opposite side (real, inverted, magnified) ✓
B. 6 cm on the opposite side (real, inverted, diminished)
C. 15 cm on the same side (virtual, erect)
D. At infinity

Answer: A. 30 cm on the opposite side (real, inverted, magnified)
Using lens formula: 1/f = 1/u + 1/v, where f = 10 cm, u = 15 cm. Solving: 1/10 = 1/15 + 1/v gives v = 30 cm. Since v is positive and greater than u, the image is real, inverted, and magnified.

A convex lens of focal length 5 cm is used as a magnifying glass. An object is placed 3 cm from the lens. What can be concluded about the image formed?

A. Real, inverted, and highly magnified (magnification > 5)
B. Virtual, erect, and magnified (magnification = 5)
C. Virtual, erect, and magnified (magnification > 5) ✓
D. Real, inverted, but diminished (magnification < 1)

Answer: C. Virtual, erect, and magnified (magnification > 5)
When object is placed between focus and lens (u < f), using lens formula with u = 3 cm and f = 5 cm gives negative v (virtual image on same side). Magnification m = -v/u is greater than 1, erect, and magnified.

Which of the following statements about critical angle and total internal reflection is INCORRECT?

A. Critical angle exists only when light travels from denser to rarer medium
B. At the critical angle, the refracted ray travels along the interface (refraction angle = 90°)
C. For angles greater than critical angle, some light is refracted out of the medium ✓
D. Critical angle is inversely related to the refractive index difference between two media

Answer: C. For angles greater than critical angle, some light is refracted out of the medium
For angles greater than the critical angle, NO light is refracted out—only total internal reflection occurs. Light does not refract beyond the critical angle.