waves

The Doppler Effect

Watch wavefronts compress ahead of a moving source and stretch behind it. See why ambulance sirens drop in pitch as they pass — interactive wavefront visualization with adjustable source speed.

Doppler

A-Level

The Doppler effect is the change in observed frequency when the source and observer are in relative motion. When a source approaches, wavefronts are compressed (higher frequency). When it recedes, they are stretched (lower frequency).

Source Speed30m/s

Frequency440Hz

📐 Formulas

f' = f\frac{v \pm v_o}{v \mp v_s}Frequency shift

\frac{\Delta f}{f} = \frac{v}{c}Red/blueshift approximation

📋 Syllabus

AQA3.3.1.1

EdexcelTopic 5