1. 1
   A student uses a loudspeaker connected to a signal generator to produce a sound wave in air. The signal generator is set to produce a note of frequency 660 Hz. The sound wave travels through the air at a speed of 330 m/s.

   (a)

   What type of wave is a sound wave?

   [1 mark]

   • ATransverse
   • BLongitudinal
   • CElectromagnetic
   • DStanding only, never travelling

   (b)

   As the sound wave travels through the air, what happens to the air particles?

   [1 mark]

   • AThey form regions of compression and rarefaction
   • BThey move permanently towards the listener
   • CThey stop vibrating once the wave has passed
   • DThey vibrate perpendicular to the direction the wave travels

   (c)

   Calculate the wavelength of the sound wave produced by the loudspeaker.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A geological survey team uses echo sounding from a boat to measure the depth of a lake. They send a pulse of sound down through the water and detect the reflected pulse 0.08 s later. The speed of sound in the water is 1500 m/s.

   (a)

   What phenomenon allows the pulse of sound to return to the boat's detector?

   [1 mark]

   • ARefraction
   • BDiffraction
   • CReflection
   • DResonance

   (b)

   What is meant by the frequency of the sound wave used in this survey?

   [1 mark]

   • AThe maximum displacement of the wave from its undisturbed position
   • BThe distance between two equivalent points on the wave
   • CThe time taken for one complete wave to pass a point
   • DThe number of waves passing a point per second

   (c)

   Calculate the depth of the lake at the point where the pulse was sent down.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A hospital ultrasound department scans a pregnant patient using an ultrasound probe that emits sound waves at a frequency of 4.5 MHz, which is above the range of human hearing.

   (a)

   Explain why the ultrasound waves used by the probe cannot be heard by the patient, and explain how the reflected waves are used to build up an image of the tissues inside the body.

   [3 marks]

   (b)

   The speed of ultrasound in soft tissue is 1540 m/s. Calculate the wavelength of the ultrasound wave in soft tissue, and explain one advantage and one disadvantage of using a higher frequency ultrasound wave for this scan.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A concert hall is being redesigned to improve the way sound reaches audience members in the back rows. Engineers are considering the acoustic properties of different wall materials and the design of the seating area.

   (a)

   Describe, using the particle model of sound wave propagation through air, how sound energy is transferred from the loudspeakers on the stage to a listener sitting at the back of the concert hall. Your answer should refer to compressions and rarefactions, amplitude, and loudness.

   [6 marks]

   (b)

   A recording engineer wants to reduce unwanted echoes in the hall. Evaluate how the choice of wall material affects the balance between reflection and absorption of sound waves, and explain how this would inform decisions about the materials used to line the walls and ceiling.

   [6 marks]

   Total for question 4: 12 marks

End of questions