IB Physics SL C.5.2 Doppler wavefront diagrams

Practise reading and sketching Doppler wavefront diagrams, showing how source motion changes wavefront spacing in front and behind.

Syllabus
First assessment 2025
Objective
—
Level
SL

Exam points

  • sketch successive circular wavefronts from moving source positions, with centres shifted in the direction of motion
  • choose the correct wavefront diagram by comparing compressed fronts ahead of the source and wider spacing behind
  • explain the drop in heard frequency after passing by linking the observer to fewer wavefronts arriving each second

C.5.2—Doppler wavefront diagrams question 1

[Maximum number: 2]

This question is about the Doppler effect.

The diagram shows wavefronts in air produced by a stationary source S of sound.
The distance between successive wavefronts is equal to the wavelength of the sound.
The speed of sound is c.

Figure for Question C.5.2—Doppler wavefront diagrams question 1 — IB Physics SL

On the diagram, sketch three successive waveforts produced when S is moving to the left at a speed of 0.5 c.

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