Practice question

**Beat formation** is interference in time with time-varying amplitude. Frequencies close together generate slow modulation, count in given duration obtained by multiplying beat frequency by duration, e.g., 6 Hz × 5 s = 30 beats. Let v₂ be the original frequency. |288 - v₂| = 3 ⇒ v₂ = 285 Hz or 291 Hz . Increasing tension increases frequency. If v₂ = 285 , new v₂’ > 285 , beat = 288 - v₂’ < 3 , becomes 1 Hz ( v₂’ = 287 ), consistent. If v₂ = 291 , beat increases, contradicts. So, v₂ = 285 Hz . Using v = fλ and