Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Light and Sound
70 practice questions
Topics covered
Practice questions
31–36 of 36 · Normal
Question 31
4 marks · Normal
Answer and see the solution →A sound wave travels from a warm region into a cooler region of air.
(a)[1 mark]Name the process that happens to the sound wave as it passes into the cooler region.
(b)[2 marks]Explain, with reference to the speed of sound, why the direction of the wave changes.
(c)[1 mark]Describe one real-life example where this process makes sounds easier to hear over long distances.
Question 32
6 marks · Normal
Answer and see the solution →A student investigates the path of a ray of light using a rectangular glass block and an oscilloscope.
(a)[2 marks]Draw a ray diagram to show the path of a ray of light entering a rectangular glass block from air at an angle. Show the angles of incidence and refraction.
(b)[2 marks]The angle of incidence is measured as 45° and the angle of refraction is 28°. Calculate the refractive index of the glass.
(c)[2 marks]Describe how the speed of sound in air can be measured in a school lab, using the reflection of sound. Name the piece of equipment you could use to display a sound wave.
Question 33
5 marks · Normal
Answer and see the solution →Optical fibres use total internal reflection to transmit light signals long distances, which is similar to how prisms are used in periscopes.
(a)[2 marks]Explain why total internal reflection occurs inside an optical fibre and draw a labelled diagram to illustrate it.
(b)[2 marks]State one medical and one communication use of optical fibres.
(c)[1 mark]A certain type of glass has a refractive index of 1.56. Calculate its critical angle for total internal reflection.
Question 34
6 marks · Normal
Answer and see the solution →When a ray of light passes from air into glass, part of the light is refracted and part is reflected. Sounds can also be reflected by surfaces.
(a)[2 marks]Complete the ray diagram below for a ray passing from air into a glass block and emerging on the other side. Draw the path through the block, marking the normals, angles of incidence and refraction.
(b)[2 marks]A ship uses echo sounding (sonar) to measure ocean depth. If the sound pulse returns after 3.0 s and the speed of sound in seawater is 1500 m/s, calculate the depth of the ocean.
(c)[2 marks]Compare the laws of reflection for light and sound. Give one difference in how each wave behaves when it meets a surface.
Question 35
5 marks · Normal
Answer and see the solution →Sound and light both travel as waves but have different properties.
(a)[2 marks]State whether light and sound are transverse or longitudinal waves respectively. Give one piece of evidence for your answer in each case.
(b)[2 marks]A sound wave has a frequency of 440 Hz and travels at 340 m/s in air. Calculate its wavelength.
(c)[1 mark]State the range of frequencies the average person can hear. Describe how loudness and pitch are represented on an oscilloscope trace of a sound wave.
Question 36
5 marks · Normal
Answer and see the solution →The diagram below shows a prism, like those used in binoculars, and a glass block. Both rely on total internal reflection.
(a)[2 marks]Describe and explain what happens to a ray of light inside a prism when it strikes the surface at an angle greater than the critical angle. Draw a labelled diagram to support your answer.
(b)[2 marks]Calculate the angle of refraction if a ray of light enters glass from air at 35° and the refractive index of glass is 1.52.
(c)[1 mark]Binoculars use prisms for total internal reflection, but sound waves cannot be 'bent' this way. Suggest one reason for this difference.