9478 / 2027

Chapter 10

Wave Motion

Identify what oscillates, which coordinate is being plotted and how energy is transferred before using a wave equation.

Read wave representations accurately and explain how propagation, spreading and polarising filters affect a wave.

Progressive mechanical and electromagnetic waves, displacement graphs and phase, wave speed, intensity and inverse-square spreading, polarisation and Malus' law. For 9478 (2027).

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  1. Propagation and particle motion

    Identify the oscillating quantity and distinguish its local motion from propagation and energy transfer.

  2. Transverse graphs and phase

    Distinguish a spatial snapshot from a fixed-point time trace and relate phase to distance and delay.

  3. Read longitudinal waves

    Connect signed longitudinal displacement, compression and separate space and time graphs.

  4. Wave speed, frequency and wavelength

    Derive v = f lambda and apply it to mechanical waves and electromagnetic waves in vacuum.

  5. Intensity and spreading

    Relate power per area to amplitude and compare distances under a point-source model.

  6. Polarisation and filter axes

    Use transverse directions and the current incident polarisation to calculate transmitted amplitude and intensity.