Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Light and Sound
70 practice questions
Topics covered
Practice questions
21–30 of 70
Question 21
2 marks · Easy
Answer and see the solution →Explain why total internal reflection does not occur when light travels from air into glass, even if the angle of incidence is large.
Question 22
3 marks · Easy
Answer and see the solution →Optical fibres are used to carry communication signals as pulses of light.
(a)[1 mark]State the role of total internal reflection in an optical fibre.
(b)[2 marks]Explain, using the idea of critical angle, how the light pulse remains inside the fibre.
Question 23
1 mark · Easy
Answer and see the solution →Complete the following sentence: A ray of light passing from glass into air will be totally internally reflected if the angle of incidence is _______ the critical angle.
Question 24
3 marks · Easy
Answer and see the solution →A triangular glass prism is used in a periscope. The refractive index of the glass is 1.50.
(a)[2 marks]Calculate the critical angle for light inside this prism. Give your answer to 2 decimal places.
(b)[1 mark]Explain why light striking the prism face at 45° is totally internally reflected.
Question 25
5 marks · Normal
Answer and see the solution →A student uses a prism made from glass with refractive index 1.52. She shines a ray of light at 49° to the normal onto the surface between glass and air.
(a)[2 marks]Calculate the critical angle for this glass–air boundary. Give your answer to 1 decimal place.
(b)[3 marks]Will the ray undergo total internal reflection at the boundary? Explain your answer with a calculation or comparison.
Question 26
2 marks · Normal
Answer and see the solution →Prisms are often used in periscopes instead of mirrors. State one advantage of using prisms over mirrors and explain why this is beneficial.
Question 27
3 marks · Normal
Answer and see the solution →Describe an experiment using a semi-circular glass block and a ray box to determine the critical angle of glass. State the steps you would take and the measurements you would make.
Question 28
1 mark · Normal
Answer and check →Which statement correctly describes total internal reflection in the context of light travelling from glass into air?
- A.It occurs when the angle of incidence is less than the critical angle.
- B.It occurs only when the angle of reflection equals the critical angle.
- C.It occurs when the angle of incidence is greater than the critical angle.
- D.It occurs for any angle when light passes from air into glass.
Question 29
3 marks · Normal
Answer and see the solution →A glass block has a refractive index of 1.48. Calculate: a) The value of sin of the critical angle. b) The value of the critical angle itself (to 2 decimal places).
Question 30
3 marks · Normal
Answer and see the solution →A laser beam is sent into an optical fibre made of glass surrounded by air. Explain why the light remains trapped inside the fibre when it travels around bends.