1. 1
   A fishing float bobs up and down on the surface of a lake as ripples pass beneath it, but the float does not travel horizontally across the lake with the ripples.

   (a)

   What does this observation demonstrate about waves?

   [1 mark]

   • AWaves transfer energy without transferring matter
   • BWaves transfer matter without transferring energy
   • CWaves cannot exist on the surface of water
   • DThe float is heavier than the surrounding water

   (b)

   As the ripples pass beneath the float, the float moves up and down, at right angles to the direction the ripples are travelling across the lake surface. What type of wave is this water ripple an example of?

   [1 mark]

   • AA transverse wave
   • BA longitudinal wave
   • CA standing wave only
   • DA sound wave

   (c)

   Define the terms wavelength and amplitude as they apply to the water ripples on the lake.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A slinky spring is stretched out along a corridor. A student pushes one end quickly forward and back along the length of the spring, creating a series of compressions and rarefactions that travel along the spring, with the coils vibrating parallel to the direction the wave travels.

   (a)

   What type of wave has the student created?

   [1 mark]

   • AA longitudinal wave
   • BA transverse wave
   • CAn electromagnetic wave
   • DA standing wave

   (b)

   Which of the following is a real-world example of a wave that behaves in the same way as the slinky spring wave described (vibration parallel to the direction of travel)?

   [1 mark]

   • AA sound wave travelling through air
   • BA water wave on the surface of the sea
   • CA visible light wave travelling through a vacuum
   • DA radio wave travelling through the atmosphere

   (c)

   Describe the appearance of the slinky spring as the longitudinal wave travels along it, referring to the terms compression and rarefaction.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A physics class uses a ripple tank to investigate water waves. A straight wooden barrier is placed diagonally across the tank, and the students observe the waves changing direction as they hit the barrier, without any change in wavelength.

   (a)

   (a) State the name given to this behaviour of the waves, and describe what causes it in terms of the direction of the wavefronts before and after they meet the barrier.

   [3 marks]

   (b)

   The students then remove the barrier and instead place a raised plastic sheet under one half of the tank, so that the water there is shallower than in the rest of the tank. They observe that as the water waves pass from the deep region into the shallow region, the wavelength of the waves becomes noticeably shorter, and the direction of the waves changes slightly if the boundary between deep and shallow water is at an angle to the wavefronts. Name and explain this second phenomenon fully, including why the wavelength changes.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An oceanographer studies water waves approaching a harbour entrance, which consists of a narrow gap between two long stone breakwaters. She observes that when long-wavelength ocean swell waves reach the gap, they spread out significantly into the harbour behind the breakwaters, whereas short-wavelength wind-generated ripples passing through the same gap spread out much less and continue mostly in their original direction.

   (a)

   Explain fully, using the concept of diffraction, why the wavelength of the waves relative to the width of the gap determines how much the waves spread out after passing through it.

   [6 marks]

   (b)

   The oceanographer also studies waves diffracting around the end of a single long breakwater (an edge, rather than a gap between two breakwaters). She finds that the long-wavelength swell waves diffract noticeably around the end of the breakwater, curving into the sheltered water behind it, while the short wind ripples diffract only slightly around the same edge. Explain fully how diffraction at a single edge compares with diffraction through a gap, and explain, using wavelength, why the same pattern (long wavelength diffracting more than short wavelength) is observed at an edge just as it was at the gap.

   [6 marks]

   Total for question 4: 12 marks

End of questions