AQA GCSE PHYSICS · PAPER 2 · HIGHER TIER ONLY
Exam Practice: Loudspeakers and headphones
Loudspeakers and headphones · Magnetism and electromagnetism · Lesson 5 of 8 · 13 marks · 14 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)
What type of current flows through the coil of a loudspeaker? Describe how the cone moves.
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(Total for Question 1 = 2 marks)
Question 2 EXPLAIN (4 marks)
Explain how a loudspeaker produces sound.
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(Total for Question 2 = 4 marks)
Question 3 EXPLAIN (2 marks)
The frequency of the alternating current is increased. State the effect on the sound.
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(Total for Question 3 = 2 marks)
Question 4 EXPLAIN (2 marks)
The amplitude of the current is increased. State the effect on the sound and explain.
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(Total for Question 4 = 2 marks)
Question 5 EXPLAIN (3 marks)
Explain why the current in a loudspeaker must be alternating rather than direct.
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(Total for Question 5 = 3 marks)
TOTAL FOR PAPER = 13 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
An alternating current. The cone moves back and forth (vibrates).
• Alternating current 1 mark
• Cone vibrates back and forth 1 mark
Question 2 (4 marks)
An alternating current flows in the coil, which is in the field of a permanent magnet. The motor effect gives a force on the coil that reverses as the current reverses. The coil and cone vibrate at the frequency of the current. The cone produces longitudinal sound waves.
• a.c. in a coil in a magnetic field 1 mark
• Motor effect force 1 mark
• Force changes direction so cone vibrates 1 mark
• Sound waves produced 1 mark
Question 3 (2 marks)
The pitch of the sound rises because the cone vibrates faster.
• Higher pitch / higher frequency 1 mark
• Cone vibrates faster 1 mark
Question 4 (2 marks)
The sound is louder because a larger current gives a larger force so the cone vibrates with a larger amplitude.
• Louder 1 mark
• Larger force or larger vibration 1 mark
Question 5 (3 marks)
A direct current would give a force in one direction, so the cone would only move once and stay there. An alternating current reverses the force so the cone moves back and forth and produces sound.
• d.c. gives a steady force in one direction 1 mark
• Cone only moves once/stays displaced 1 mark
• a.c. reverses the force so the cone vibrates 1 mark