What are wavefronts?
3 marks · NormalA sound wave has a frequency of 400 Hz. Calculate the period of one vibration.
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T = 1 / f = 1 / 400 = 0.0025 s (±0.0001)
Must show: Working using the formula T=1/f; correct substitution; correct final answer with unit
Common mistakes: Not inverting frequency; Calculator input error
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Marking points
M1 · 1 mark · Correctly writes or identifies the formula T = 1/f.
M2 · 1 mark · Correct substitution of f = 400 Hz.
A1 · 1 mark · Calculates T = 0.0025 s (accept 2.5 × 10⁻³ s); correct units.
Worked solution