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12 marksProperties of Waves

CAPE Physics Unit 1 · 2001 · Paper 2 · Question 6(c)(i)

In an auditorium, two loudspeaker boxes are placed as shown in Figure 2, emitting identical sounds of frequency 1.4 kHz. The sound intensity reaches a maximum of 40 dB above the threshold of hearing along the line PQR. Velocity of sound = 350 m s⁻¹.

Determine the positions along the line PQR where destructive interference causes the intensity to fall to zero.

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Other parts of this question

  1. 6(a)Explain what is meant by the loudness of a sound.[2 marks]
  2. 6(b)Describe with the aid of diagrams the response of the ear to sound waves in terms of frequency, intensity and loudness level.[6 marks]
  3. 6(c)(ii)Calculate the intensity in Wm⁻² of the sound at the point Q.[1 mark]

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