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Optics: Reflection, Refraction, and Lenses — High School Physics practice questions

14 multiple-choice questions and 15 flashcards on Optics: Reflection, Refraction, and Lenses, about 9% of the High School Physics bank. Every one carries a written rationale.

Written and maintained by the CoStudy team · last updated 2026-10-12 · how we write and review questions

What this chapter covers

Optics: Reflection, Refraction, and Lenses is one of 11 chapters in CoStudy's High School Physics bank, and it holds 14 of the bank's 150 multiple-choice questions — roughly 9% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Optics: Reflection, Refraction, and Lenses practice questions

6 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

A prism separates white light into colors because:

  1. the prism adds color to the light
  2. light reflects inside the prism only
  3. each wavelength refracts by a different amount
  4. all colors travel at the same speed in glass

Answer: C — each wavelength refracts by a different amount

C) Correct — This is dispersion. A) White light already contains the colors. B) Refraction separates the colors. D) They travel at slightly different speeds.

Fiber-optic cables carry light using:

  1. diffraction
  2. dispersion
  3. absorption
  4. total internal reflection

Answer: D — total internal reflection

D) Correct — Light hits the core's edge beyond the critical angle. A) Is spreading. B) Is separation of colors. C) Would lose the signal.

The image in a flat (plane) mirror is:

  1. real and inverted
  2. magnified
  3. virtual, upright, and the same size
  4. virtual and inverted

Answer: C — virtual, upright, and the same size

C) Correct — It appears as far behind the mirror as the object is in front. A) Plane mirrors don't form real images. B) It is the same size. D) It is upright.

A converging lens has f = 10 cm. An object is 30 cm away. Where is the image?

  1. 20 cm
  2. 15 cm from the lens
  3. 7.5 cm
  4. 40 cm

Answer: B — 15 cm from the lens

B) Correct — 1/dᵢ = 1/10 − 1/30 = 2/30. A) Subtracts the distances. C) Adds the reciprocals. D) Adds the distances.

By the law of reflection:

  1. the angle of reflection is always 90°
  2. light speeds up when it reflects
  3. the angle of incidence equals the angle of reflection
  4. the angle of incidence doubles

Answer: C — the angle of incidence equals the angle of reflection

C) Correct — Both are measured from the normal. A) Not true. B) Speed doesn't change. D) Not true.

Light travels at 2.0 × 10⁸ m/s in a material. What is the index of refraction? (c = 3.0 × 10⁸ m/s)

  1. 0.67
  2. 1.5
  3. 6.0
  4. 1.0

Answer: B — 1.5

B) Correct — n = c/v = 3/2. A) Divides v by c. C) Multiplies. D) Is the index of a vacuum.

Optics: Reflection, Refraction, and Lenses flashcards

4 cards from the 15 in this chapter.

What is refraction?

The bending of light as it passes from one medium to another due to a change in speed.

What kind of lens spreads parallel light apart?

A diverging (concave) lens.

Write the thin-lens / mirror equation.

1/f = 1/d_o + 1/d_i, where f is focal length, d_o object distance, d_i image distance.

What kind of lens converges parallel light to a point?

A converging (convex) lens.

Practise the full chapter

These are a sample. The full Optics: Reflection, Refraction, and Lenses chapter runs 29 items with per-chapter progress tracking, on the web and in the iOS app.

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