Beat Frequency (ν_beat = |ν₁ - ν₂|)
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ν_beat = |ν₁ - ν₂|
What each symbol means
| Symbol | What it stands for |
|---|---|
| ν₁ | Frequency of first source (Hz) |
| ν₂ | Frequency of second source (Hz) |
| ν_beat | Beat frequency — number of beats per second (Hz) |
When to use this
Beats occur when two waves of slightly different frequencies superpose. Perceived as periodic waxing and waning of sound intensity. Amplitude varies as cos((ω₁-ω₂)t/2). Beats are audible only when |ν₁ - ν₂| < ~10 Hz. Used for tuning instruments. If tension is increased and beat frequency decreases, then that string had lower frequency. NCERT Eq. 14.48.