Describing waves
4 marks · NormalA student makes waves on the surface of a pool by repeatedly dipping her finger up and down in the water.
State what is meant by a transverse wave.
Describe, with reference to this situation, how the direction of vibration of the water relates to the direction in which the wave moves.
Name another example of a transverse wave (other than water waves).
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(a) A transverse wave is one where the vibrations are at right angles (perpendicular) to the direction in which the wave or energy travels.
(b) The water surface moves up and down (vibrates vertically) while the wave moves outwards across the pool (horizontally), so the vibrations are at right angles to the direction of wave travel.
(c) Light (wave), or electromagnetic wave, or any surface wave on a string.
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Marking points
B1 (a) · 1 mark · Defines a transverse wave correctly: vibrations at right angles (perpendicular) to the direction of travel.
B1 (b) · 1 mark · States that the water moves up and down/vibrates vertically.
B1 (b) · 1 mark · States that the wave travels along/across the pool or horizontally, at right angles to the vibration direction.
B1 (c) · 1 mark · Gives a correct example of a transverse wave (e.g. light wave/EM wave/string surface wave).
Worked solution
a) A transverse wave is one in which vibrations are at right angles to the direction the wave or energy is travelling.
b) In this case, the water at the surface vibrates up and down (vertically) while the wave itself moves across the surface of the pool (horizontally), so the direction of vibration is perpendicular to the direction the wave travels.
c) Another example of a transverse wave is light, an electromagnetic wave, or a surface wave on a string.