Pearson Edexcel International GCSE (9–1) · PHYSICS · Section
Optical Fibres
16 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
2 marks · Normal
Answer and see the solution →Describe the main structure of an optical fibre. Name the two main parts and their roles.
Question 2
1 mark · Normal
Answer and check →Which of the following is a correct statement about total internal reflection in an optical fibre?
- A.It can occur only when light travels from a region of lower to higher refractive index.
- B.It occurs whenever light enters an optical fibre, regardless of angle.
- C.It keeps light inside the core of the fibre if the angle is greater than the critical angle.
- D.It allows light to escape from the sides of the fibre easily.
Question 3
3 marks · Normal
Answer and see the solution →Explain how total internal reflection inside an optical fibre ensures that light follows the path of the fibre even if it bends.
Question 4
2 marks · Normal
Answer and see the solution →A telecommunications company wants to replace copper wires with optical fibres. Give two reasons, based on physics, why optical fibres are better for transmitting signals over long distances.
Question 5
4 marks · Normal
Answer and see the solution →The diagram below shows a simplified optical fibre.
Simplified cross-section of an optical fibre. (a)[1 mark]Label the core and cladding on the diagram.
(b)[2 marks]Draw a path to show how light travels along the optical fibre, reflecting from the core–cladding boundary.
(c)[1 mark]Explain why the light remains in the core as it travels.
Question 6
4 marks · Normal
Answer and see the solution →Read the passage: 'A bundle of optical fibres is used in a medical endoscope to allow a doctor to see inside a patient’s stomach.'
(a)[2 marks]Describe how the endoscope uses optical fibres to allow the doctor to see inside the body.
(b)[2 marks]State two reasons why using an endoscope made with optical fibres is an advantage for the patient, compared to traditional open surgery.
Question 7
2 marks · Normal
Answer and see the solution →State two different applications of optical fibres, other than medical endoscopes, and briefly describe how they work.
Question 8
4 marks · Normal
Answer and see the solution →A laser sends light into an optical fibre at an angle of incidence of 72° to the normal. The critical angle for the core–cladding boundary is 60°.
(a)[2 marks]Explain whether the light will be totally internally reflected at the core–cladding boundary.
(b)[2 marks]If the refractive index of the core is 1.50, calculate the maximum refractive index of the cladding for total internal reflection to occur at this boundary. (Give your answer to 2 decimal places.)