Doppler Effect
Change in observed frequency due to relative motion between source and observer.
### General Formula
$$f'=f\frac{v\pm v_o}{v\mp v_s}$$
### Terminologies
- f' → Observed frequency.
- f → Actual frequency.
- v → Velocity of sound.
- vo → Velocity of observer.
- vs → Velocity of source.
### Conditions / Special Cases
- Observer moving towards source:
$$+v_o$$
- Source moving towards observer:
$$+v_s$$
### Usage
- Used in sound frequency change problems.