Light — Reflection and Refraction — Class 10 MCQs with Answers

Light — Reflection and Refraction — important questions & MCQs with answers (Class 10 Science (Physics))

14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.

1. Q1Easy

   The image formed by a plane mirror is:

   A.Real and inverted

   B.Real and erect

   C.Virtual and erect✓ Correct

   D.Virtual and inverted

   Answer: C. Virtual and erect

   Explanation: Reflected rays from a plane mirror only appear to meet behind it, so the image is virtual and erect, same size as the object — never real or inverted, unlike a curved mirror.

2. Q2Easy

   A convex lens is also called:

   A.Converging lens✓ Correct

   B.Diverging lens

   C.Plane lens

   D.Concave lens

   Answer: A. Converging lens

   Explanation: A convex lens converges parallel rays to a focal point — converging lens.

3. Q3Easy

   The SI unit of power of a lens is:

   A.Metre

   B.Lumen

   C.Watt

   D.Dioptre✓ Correct

   Answer: D. Dioptre

   Explanation: Power P = 1/f (in metres). 1 dioptre = 1 m⁻¹.

4. Q4Easy

   Image formed by a plane mirror is:

   A.Smaller

   B.Real, inverted

   C.Virtual, erect, same size✓ Correct

   D.Larger

   Answer: C. Virtual, erect, same size

   Explanation: A plane mirror's reflected rays diverge as if coming from behind the glass, forming a virtual, erect image exactly as far behind the mirror as the object is in front — never real.

5. Q5Easy

   Mirror formula is:

   A.1/v + 1/u = 1/f✓ Correct

   B.1/v − 1/u = 1/f

   C.v + u = f

   D.v/u = f

   Answer: A. 1/v + 1/u = 1/f

   Explanation: The mirror formula 1/v + 1/u = 1/f links object distance, image distance and focal length, using the convention where distances against the incident light are negative.

6. Q6Easy

   Magnification m for mirrors is:

   A.v/u

   B.−v/u or h'/h✓ Correct

   C.−u/v

   D.u + v

   Answer: B. −v/u or h'/h

   Explanation: Linear magnification for a mirror is m = −v/u = h'/h; the minus sign means a virtual, erect image (v positive, u negative) still comes out with positive m, matching its upright form.

7. Q7Medium

   The mirror formula relates u, v, f as:

   A.1/v + 1/u = 1/f✓ Correct

   B.1/v − 1/u = 1/f

   C.u + v = f

   D.u − v = f

   Answer: A. 1/v + 1/u = 1/f

   Explanation: Mirror formula: 1/v + 1/u = 1/f, with u and v signed per convention. It's easy to confuse with the lens formula's 1/v − 1/u = 1/f, which carries a minus sign instead.

8. Q8Medium

   A convex lens has focal length 50 cm. Its power is:

   A.+0.02 D

   B.+2 D✓ Correct

   C.+20 D

   D.−2 D

   Answer: B. +2 D

   Explanation: P = 1/f(in m) = 1/0.50 = +2 D. Convex → positive.

9. Q9Medium

   Snell's law of refraction states:

   A.n₁ + n₂ = sin i + sin r

   B.sin i × sin r = constant

   C.n₁ sin i = n₂ sin r✓ Correct

   D.i = r

   Answer: C. n₁ sin i = n₂ sin r

   Explanation: Snell's law states n₁ sin i = n₂ sin r, linking each medium's refractive index to the angle from the normal — not the mirror rule i = r, which applies only to reflection.

10. Q10Medium

    For a concave mirror, when object is at infinity, image is:

    A.Same size

    B.At centre of curvature

    C.At focus, highly diminished, real, inverted✓ Correct

    D.At pole

    Answer: C. At focus, highly diminished, real, inverted

    Explanation: Parallel rays from a very distant object converge exactly at a concave mirror's focus, producing a highly diminished, real, inverted image there — not at the centre of curvature.

11. Q11Medium

    Object placed 30 cm in front of a concave mirror of focal length 10 cm. Image distance v:

    A.30 cm

    B.+15 cm

    C.−15 cm✓ Correct

    D.60 cm

    Answer: C. −15 cm

    Explanation: 1/v = 1/f − 1/u = 1/(−10) − 1/(−30) = −3/30 + 1/30 = −2/30 ⇒ v = −15 cm. (Real image on same side.)

12. Q12Hard

    An object placed at the focus of a concave mirror produces an image:

    A.At infinity, real, highly enlarged✓ Correct

    B.At the focus, real, same size

    C.Behind the mirror, virtual

    D.At the centre of curvature

    Answer: A. At infinity, real, highly enlarged

    Explanation: Rays from an object at a concave mirror's focus reflect parallel to the axis and never reconverge to a finite point, so the image forms at infinity — real, inverted and highly magnified.

13. Q13Hard

    An object placed exactly at the focus of a convex lens gives an image:

    A.At the optical centre

    B.Coinciding with the object

    C.At the focus on the other side

    D.At infinity✓ Correct

    Answer: D. At infinity

    Explanation: Rays from an object at the focus emerge parallel after refraction, so the image is formed at infinity.

14. Q14Hard

    Refractive index of glass with respect to air is 1.5. The speed of light in glass is approximately:

    A.3 × 10⁸ m/s

    B.2 × 10⁸ m/s✓ Correct

    C.4.5 × 10⁸ m/s

    D.1.5 × 10⁸ m/s

    Answer: B. 2 × 10⁸ m/s

    Explanation: v = c / n = (3 × 10⁸) / 1.5 = 2 × 10⁸ m/s.

Light — Reflection and Refraction — FAQs

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