MCQ
Two close organ pipe having length $20\,cm$ and $20.5\, cm$ produce $5\, beats/sec$. Determine the frequency of both organ pipe
- ✓$205\, Hz, 200\, Hz$
- B$324\, Hz, 320\, Hz$
- C$155\, Hz, 150\, Hz$
- D$105\, Hz, 100\, Hz$
✓
Answer
Correct option: A.
$205\, Hz, 200\, Hz$
a
$\mathrm{n} \propto \frac{1}{\ell} \quad \frac{\mathrm{n}_{1}}{\mathrm{n}_{2}}=\frac{\ell_{2}}{\ell_{1}}$
$\mathrm{n} \propto \frac{1}{\ell} \quad \frac{\mathrm{n}_{1}}{\mathrm{n}_{2}}=\frac{\ell_{2}}{\ell_{1}}$
$\frac{\mathrm{N}}{\mathrm{N}+5}=\frac{20}{20.5}$
$20.5 \mathrm{N}=20 \mathrm{N}+5 \times 20$
$0.5 \mathrm{N}=100$
$\mathrm{N}=\frac{100}{0.5}=200 \mathrm{\,Hz}$
$\mathrm{N}+5 \Rightarrow 200+5=205 \mathrm{\,Hz}$
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