A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a source of 1237.5 Hz ?(sound velocity in air = 330 m/s)

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Answered by

Payal Gupta | Contributor-Level 10

4 months ago

This is a short answer type question as classified in NCERT Exemplar

length of pipe

L=20cm =20 $\times 10^{- 2} m$

$v_{c l o s e} = \frac{v}{4 L} = \frac{330}{4 \times 20 \times 10^{- 2}}$

$v_{c l o s e} = 330 \times \frac{100}{80} = 412.5 H z$

$\frac{v_{g i v e n}}{v_{c l o s e d}} = 1237.5 / 412.5$ =3

Hence 3^rd harmonic node of the pipe is resonantly excited by the source of the given frequency.

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