CAIE A-Level Physics 7.1.5 Wave-Speed Calculations

Practise calculating and rearranging v = f lambda for mechanical or electromagnetic waves, using measured data and interpreting speed, frequency and wavelength.

Exam points

calculate wave speed, frequency or wavelength using v = fλ with consistent units
rearrange v = fλ and use measured or graphical wavelength and period data
interpret changes in wave speed, frequency and wavelength in a stated medium

[Maximum number: 2]

The frequency of the wave in (a) is 16 kHz . The distance between particles X and Y is 0.19 m .

Calculate the speed of the wave as it travels through the medium. $\mathrm{ms}^{-1}$

$\begin{aligned} \lambda =2 \times 0.19 =0.38 \mathrm{~m} \end{aligned}$

C1

$v=f \lambda$

C1

$\begin{aligned} v=\left(16 \times 10^{3}\right) \times 0.38 v=6100 \mathrm{~m} \mathrm{~s}^{-1} \end{aligned}$

A1

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7.1.5—V = f λ question 1