AQA · GCSE · Combined Science · Higher

Water depth and wave wavelength

Q03.4 2 marks

The speed of the wave is affected by the depth of the water in the ripple tank. The deeper the water the faster the wave. Explain how the depth of the water affects the wavelength of the wave if the frequency is constant.

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Marking points

1 State that deeper water gives a longer wavelength.
2 Explain this using $v=f\lambda$ : the speed increases while the frequency stays constant, so the wavelength must increase.

Full-mark answer

In deeper water the wavelength is longer. This is because the wave speed increases, and if the frequency is constant then $v=f\lambda$ means the wavelength must increase.

Why this answer loses marks

The wavelength gets shorter because the waves move faster.

If frequency is constant, a higher wave speed means a longer wavelength, not a shorter wavelength.

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