IB Physics SL C.5 Doppler Effect Question Bank
Practise predicting Doppler shifts for sound and light, applying the low-speed light approximation and interpreting spectral evidence for relative motion.
- Syllabus
- First assessment 2025
- Topic
- —
- Level
- SL
Exam points
- predict redshift, blueshift or sound-frequency change from approach, recession and wavefront spacing
- apply Δλ/λ≈v/c to calculate low-speed light shifts, radial speed or reflected-radar change
- interpret shifted spectral lines to infer stellar motion, rotation, expansion or Hubble-law distance
Covered syllabus points
C.5 Doppler effect question 1
This question is about the Doppler effect.
Georgia carries out an experiment to measure the speed of mosquitoes. She sets up a microphone to record the sounds of passing mosquitoes.
One mosquito is moving in a straight line with constant speed and passes very close to the microphone as seen in the diagram. The mosquito produces a sound of constant frequency. The speed of sound in air is .
The maximum frequency recorded is 751 Hz and the minimum frequency recorded is 749 Hz . Explain this observation.
C.5 Doppler effect question 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.
On the diagram, sketch three successive waveforts produced when S is moving to the left at a speed of 0.5 c.
C.5 Doppler effect question 3
Star A is a main sequence star.
The data for Star A and the Sun are given in a table.
Determine the speed, in , of Star A relative to Earth.
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