1. 1
   A rope is shaken from side to side so that a wave travels along its length. A student watches the wave pass a fixed knot tied to the rope and times how long it takes for 20 complete oscillations of the knot to occur, obtaining a time of 8 seconds.

   (a)

   Which type of wave is produced when a rope is shaken from side to side?

   [1 mark]

   • AA longitudinal wave, because the knot moves parallel to the direction of energy transfer
   • BA transverse wave, because the knot moves at right angles to the direction of energy transfer
   • CA longitudinal wave, because the rope itself travels along with the wave
   • DA transverse wave, because the wave cannot transfer energy without transferring matter

   (b)

   What is the frequency of the wave on the rope, calculated from the student's timing of 20 oscillations in 8 seconds?

   [1 mark]

   • A0.4 Hz
   • B28 Hz
   • C160 Hz
   • D2.5 Hz

   (c)

   The student measures the wavelength of the wave on the rope as 0.6 m. Calculate the speed of the wave, using the frequency found in part (b). State the equation you use, show your working and give the unit of your final answer.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A loudspeaker produces a sound wave that travels through air as a series of compressions and rarefactions. A microphone placed 340 m from the loudspeaker detects the sound 1 second after it was emitted.

   (a)

   Which statement correctly describes the type of wave produced by the loudspeaker?

   [1 mark]

   • AIt is a transverse wave, because air particles vibrate at right angles to the direction of travel
   • BIt is a longitudinal wave, because air itself moves from the loudspeaker to the microphone
   • CIt is a longitudinal wave, because air particles vibrate parallel to the direction of travel
   • DIt is a transverse wave, because compressions and rarefactions can only form in transverse waves

   (b)

   Using the distance and time given, what is the speed of the sound wave travelling from the loudspeaker to the microphone?

   [1 mark]

   • A340 m/s
   • B170 m/s
   • C680 m/s
   • D34 m/s

   (c)

   The loudspeaker is set to emit a sound wave with a wavelength of 0.85 m. Using the speed found in part (b), calculate the frequency of the sound wave. State the equation you use, show your working and give the unit of your final answer.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A beam of light travelling through air strikes the flat surface of a block of glass. Some of the light is reflected back into the air, some is absorbed by the glass, and the remainder is transmitted into the glass, changing direction as it does so.

   (a)

   Explain, in terms of wave speed, why the light changes direction as it enters the glass. Your answer should refer to the term refraction.

   [3 marks]

   (b)

   The glass block is replaced with a block made from a different transparent material, and the experiment is repeated using red light and then blue light. The proportions of light reflected, absorbed and transmitted are found to differ between the red and blue light. Explain why different substances can absorb, transmit, refract or reflect waves in ways that vary with wavelength, and describe how the student could investigate this experimentally without using any diagrams or ray-tracing equipment.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A technician wants to measure the speed of sound in air using apparatus set up in a long, straight corridor. She stands at one end of the corridor with a starting pistol and a stopwatch, while a second technician stands 200 m away holding a large sheet of card.

   (a)

   Describe a method, using only the apparatus described (no diagrams, graphs or additional equipment beyond a stopwatch, a starting pistol and a metre rule), by which the speed of sound in air could be determined, and explain the sources of error in the method and how they could be reduced.

   [6 marks]

   (b)

   The technicians repeat the experiment using ripples on the surface of water in a long, straight water tank instead of sound in the corridor. Describe how the method and the equipment needed would need to be adapted to measure the velocity of ripples on the water surface, and explain one similarity and one difference between measuring the velocity of water waves in this way and measuring the velocity of sound as in part (a).

   [6 marks]

   Total for question 4: 12 marks

End of questions