AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER
Exam Practice: Refraction of waves
Refraction of waves · Waves · Lesson 4 of 12 · 15 marks · 16 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 STATE (2 marks)
A ray of light passes from air into a glass block. Describe what happens to the speed of the light and the direction of the ray.
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(Total for Question 1 = 2 marks)
Question 2 COMPLETE THE DIAGRAM (3 marks)
The diagram shows a ray of light hitting a glass block. Complete the diagram to show the path of the ray through the block and out of the other side.
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(Total for Question 2 = 3 marks)
Question 3 EXPLAIN (3 marks)
Explain why a wave is refracted when it crosses the boundary between two media at an angle.
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(Total for Question 3 = 3 marks)
Question 4 DESCRIBE (5 marks)
Describe an investigation to show how a ray of light is refracted by a glass block. Your answer should include the measurements you would take and what you would conclude.
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(Total for Question 4 = 5 marks)
Question 5 EXPLAIN (2 marks)
A wave travels from deep water to shallow water where it slows down. State what happens to the frequency and the wavelength.
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(Total for Question 5 = 2 marks)
TOTAL FOR PAPER = 15 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
The speed decreases, and the ray bends towards the normal.
• Speed decreases 1 mark
• Bends towards the normal 1 mark
Question 2 (3 marks)
The ray bends towards the normal entering the glass, then bends away from the normal leaving the block, emerging parallel to the incident ray.
• Bends towards the normal inside the glass 1 mark
• Bends away from the normal on leaving 1 mark
• Emergent ray parallel to the incident ray 1 mark
Question 3 (3 marks)
The speed of the wave changes when it enters the new medium. This changes the direction of the wave, because the wavefront slows down (or speeds up) first at one side.
• Speed changes in the new medium 1 mark
• Part of the wavefront changes speed first 1 mark
• So the direction changes 1 mark
Question 4 (5 marks)
Place a glass block on white paper and draw around it. Shine a narrow ray from a ray box at an angle to a face. Mark the incident ray, the emergent ray and draw the ray through the block by joining the points. Draw the normal and measure the angles of incidence and refraction with a protractor. Repeat for different angles. The ray bends towards the normal entering the glass.
• Ray box, glass block on paper, outline drawn 1 mark
• Incident and emergent rays marked 1 mark
• Normal drawn, angles measured 1 mark
• Repeat for different angles 1 mark
• Conclusion: bends towards the normal in glass 1 mark
Question 5 (2 marks)
The frequency stays the same. The wavelength decreases (v = fλ).
• Frequency unchanged 1 mark
• Wavelength decreases 1 mark