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Waves — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsWaves1 Mark
MCQ
Following two wave trains are approaching each other.
$\text{y}_1=\text{a}\sin2000\pi\text{t}$, $\text{y}_2=\text{a}\sin2008\pi\text{t}$ The number of beats heard per second is:
  • A
    $8$
  • ✓
    $4$
  • C
    $1$
  • D
    Zero
✓

Answer

Correct option: B.
$4$
Beat frequency $=\text{f}_2-\text{f}_1$
$=\frac{\omega_2-\omega_1}{2\pi}$
$=\frac{2008\pi-2000\pi}{2\pi}$
$=4\text{Hz}$

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