A closed organ pipe and an open organ pipe have their first overtones identical in frequency. Their lengths…

A closed organ pipe and an open organ pipe have their first overtones identical in frequency. Their lengths are in the ratio
  1. $3: 4$
  2. $2: 3$
  3. $4: 5$
  4. $1: 2$

Solution

First overtone of a closed pipe is given by $\mathrm{f}=\frac{3 \mathrm{~V}}{4 \ell}$ First overtone of an open pipe is given by $\mathrm{f}^{\prime}=\frac{\mathrm{V}}{\ell^{\prime}}$ Since $\mathrm{f}=\mathrm{f}^{\prime}, \quad \frac{3 \mathrm{~V}}{4 \ell}=\frac{\mathrm{V}}{\ell^{\prime}}$ $\therefore \frac{\ell}{\ell^{\prime}}=\frac{3}{4}$

Asked in: MHT CET 2020 (13 Oct Shift 1)

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