Pearson Edexcel International GCSE
Physics — Topic 3 Paper 2
Waves · specification 3.1–3.23
Time allowed: 30 minutes
Total marks: 25
Candidate name:
Centre / class:
Answer all questions. You may use a calculator. Show your working. Take the speed of electromagnetic waves in free space as $3.0 \times 10^8\,\text{m/s}$.
1
A radio mast broadcasts at a frequency of $150\,\text{MHz}$.
(a) Explain the difference between a transverse wave and a longitudinal wave. State which type a radio wave is.
[3]
(b) Calculate the wavelength of the radio wave in air.
[3]
(Total for Question 1 = 6 marks)
2
A student sends a ray of light from air into a perspex block. $i=35^\circ$ and $r=22^\circ$.
(a) On a ray diagram, from which line should $i$ and $r$ be measured?
[1]
(b) Calculate the refractive index of the perspex.
[3]
(c) For perspex, $n=1.49$. Calculate the critical angle at a perspex–air boundary.
[3]
(Total for Question 2 = 7 marks)
3
Microwaves are used for satellite transmissions. Visible light can be sent along an optical fibre.
(a) State one other specification use of microwaves.
[1]
(b) State the two conditions for total internal reflection in the fibre.
[2]
(c) Explain one hazard of excessive microwave exposure and how a person can be protected.
[3]
(Total for Question 3 = 6 marks)
4
The same student measures $n$ for the perspex block using a ray box.
(a) Describe how the student should mark the path of the ray through the block after the block is removed.
[3]
(b) The student uses only $i=8^\circ$. Explain why this is a poor choice, and state one improvement.
[3]
(Total for Question 4 = 6 marks)
END OF PAPER 2