Edexcel IGCSEPhysicsGeneral Applications9 Marks
A student uses a loudspeaker to produce sound waves.
- (a)Explain how a loudspeaker produces sound waves.[4]
- (b)The student adjusts the frequency of the sound waves produced by the loudspeaker. (i) Describe how the adjustment affects the sound waves.[1]
- (b)(ii)The student adjusts the amplitude of the sound waves produced by the loudspeaker. Describe how the adjustment affects the sound waves.[1]
- (c)The student then uses a microphone and an oscilloscope to display the sound waves from the loudspeaker, as shown in Figure 15. [Figure 15 shows a microphone connected to an oscilloscope, displaying a sinusoidal waveform.] (i) Explain how the microphone produces an electrical signal from a sound wave.[3]
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Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- Question 21(a)
- alternating current flows through coil (1)
- coil becomes an electromagnet / magnetic field around coil (1)
- magnetic field (of coil) interacts with (field of) permanent magnet (1)
- causes coil / cone to vibrate (1)
- creates compressions and rarefactions / causes air particles to vibrate (1)
- Max 4 marks
- Question 21(b)(i)
- pitch changes (1)
- Question 21(b)(ii)
- loudness / volume changes (1)
- Question 21(c)(i)
- sound waves cause diaphragm to vibrate (1)
- coil vibrates (in magnetic field) (1)
- induces a potential difference / current (1)
- OR
- sound waves cause crystal to vibrate (1)
- vibrations cause crystal to generate p.d. (1)
- due to piezoelectric effect (1)
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