The Doppler effect

3 marks · Normal

The speed of sound in a material is 1500 m/s. Calculate the frequency of a sound wave in this material if its wavelength is 2.0 m. Give your answer to 2 significant figures.

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750 Hz (±5)

Also accept: 750.0

Common mistakes: Multiplying instead of dividing; Not converting units

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Marking points

M1 · 1 mark · Writes down or states the correct formula: v = fλ or f = v/λ.

M2 · 1 mark · Substitutes v = 1500 m/s and λ = 2.0 m.

A1 · 1 mark · Evaluates frequency as 750 Hz or 2 sig fig equivalent.

Worked solution