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

The 20 questions

1. Which equation correctly defines the refractive index n of a material?

   • n = 1 / v
   • n = c / v
   • n = c x v
   • n = v / c

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. How does a light ray bend when entering a medium of higher refractive index?

   • Towards the normal
   • Along the boundary
   • Parallel to boundary
   • Away from normal

4. Total internal reflection can only occur when light travels towards a medium with what relative refractive index?

   • Zero refractive index
   • Equal refractive index
   • Lower refractive index
   • Higher refractive index

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. Which property of a light wave remains constant when it passes from air into glass?

   • Speed
   • Amplitude
   • Wavelength
   • 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) hits a glass-air boundary at 45 degrees incidence. What happens?

    • Refraction into air
    • Total internal reflection
    • Diffraction along boundary
    • Absorption in glass

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. How does a light ray bend when entering a lower refractive index medium?

    • Away from normal
    • Along the normal
    • Reflected internally
    • Towards the normal

17. Light in water (n = 1.33) hits a water-air boundary at 40 degrees. What is the angle of refraction?

    • 49 degrees
    • 30 degrees
    • 59 degrees
    • 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

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