Lesson 5.3.2

5.3.2 Refraction, critical angle and total internal reflection Quiz: Pearson Edexcel Physics, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 5.3.2, Refraction, critical angle and total internal reflection: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 5: Waves and Particle Nature of Light, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. How is the refractive index n of a material defined?

    • n = c minus v
    • n = c/v, the speed of light in a vacuum divided by its speed in the material
    • n = c times v
    • n = v/c, the speed in the material divided by the speed in a vacuum

  2. Which equation is Snell's law for refraction at an interface between media 1 and 2?

    • n1 sin(theta1) = n2 sin(theta2)
    • n1 tan(theta1) = n2 tan(theta2)
    • n1 sin(theta2) = n2 sin(theta1)
    • n1 cos(theta1) = n2 cos(theta2)

  3. When light enters a medium of higher refractive index, what happens to the ray?

    • It bends towards the normal
    • It is always totally internally reflected
    • It passes straight through without deviation
    • It bends away from the normal

  4. Total internal reflection can occur only when light travels from which kind of medium to which kind?

    • From one medium into another of the same refractive index
    • From a vacuum into glass
    • From a denser medium into a less dense medium
    • From a less dense medium into a denser medium

  5. For a material surrounded by air or a vacuum, which expression gives the critical angle C?

    • sin C = n
    • cos C = 1/n
    • tan C = n
    • sin C = 1/n

  6. What is the speed of light in glass of refractive index 1.5? Take c = 3.0 x 10^8 m/s.

    • 3.0 x 10^8 m/s
    • 2.0 x 10^8 m/s
    • 1.5 x 10^8 m/s
    • 4.5 x 10^8 m/s

  7. When light passes from air into glass, which quantity is unchanged?

    • Wavelength
    • Both speed and wavelength
    • Speed
    • Frequency

  8. Light is incident at 30 degrees from air on a material with refractive index 1.5. What is the angle of refraction?

    • 45.0 degrees
    • 12.0 degrees
    • 30.0 degrees
    • 19.5 degrees

  9. What is the critical angle for light travelling from glass of refractive index 1.5 into air?

    • 33.7 degrees
    • 48.6 degrees
    • 41.8 degrees
    • 56.3 degrees

  10. What is the critical angle for light travelling from water of refractive index 1.33 into air?

    • About 49 degrees
    • About 41 degrees
    • About 60 degrees
    • About 37 degrees

  11. What is the speed of light in water of refractive index 1.33? Take c = 3.0 x 10^8 m/s.

    • 4.0 x 10^8 m/s
    • 1.3 x 10^8 m/s
    • 2.3 x 10^8 m/s
    • 3.0 x 10^8 m/s

  12. Light of wavelength 600 nm in air enters glass of refractive index 1.5. What is its wavelength in the glass?

    • 200 nm
    • 400 nm
    • 900 nm
    • 600 nm

  13. Light in glass (n = 1.5) meets a glass-air boundary at an angle of incidence of 45 degrees. What happens?

    • Refraction occurs, because 45 degrees is less than the critical angle of 41.8 degrees
    • Total internal reflection occurs, because 45 degrees exceeds the critical angle of 41.8 degrees
    • Refraction occurs with an angle of refraction of 45 degrees
    • Total internal reflection occurs, because 45 degrees is less than 41.8 degrees

  14. Light passes from air into a glass block at 60 degrees to the normal. The refractive index of the glass is 1.5. What is the angle of refraction?

    • 25.0 degrees
    • 35.3 degrees
    • 40.0 degrees
    • 60.0 degrees

  15. A ray in air strikes a material at 50 degrees to the normal and is refracted to 30 degrees. What is the refractive index of the material?

    • 1.53, about 1.5
    • 2.00
    • 0.65
    • 1.00

  16. A student says that light always bends towards the normal when it enters any medium. Which evaluation is correct?

    • Incorrect, because light bends towards the normal only on entering a higher-index medium; entering a lower-index medium bends it away
    • Correct, because light slows down in every medium so it always bends towards the normal
    • Incorrect, because light never bends at a boundary
    • Correct, because refraction always bends light towards the normal

  17. Light in water (n = 1.33) meets the water-air surface at 40 degrees to the normal. What is the angle of refraction in air?

    • Total internal reflection occurs
    • About 31 degrees
    • About 59 degrees
    • About 40 degrees

  18. An optical fibre has core refractive index 1.50 and cladding refractive index 1.45. What is the critical angle at the core-cladding boundary?

    • About 58 degrees
    • About 15 degrees
    • About 82 degrees
    • About 75 degrees

  19. Light travels 0.20 m through glass of refractive index 1.5. How long does it take? Take c = 3.0 x 10^8 m/s.

    • 2.0 x 10^-9 s
    • 6.7 x 10^-10 s
    • 3.0 x 10^-9 s
    • 1.0 x 10^-9 s

  20. A material has a critical angle of 42 degrees when surrounded by air. What is its refractive index?

    • About 0.67
    • About 1.5
    • About 1.0
    • About 2.0

All Pearson Edexcel Physics quizzes