In fundamental mode, the time required for the sound wave to reach up to the closed end of pipe filled with…

In fundamental mode, the time required for the sound wave to reach up to the closed end of pipe filled with air is $t$ second. The frequency of vibration of air column is
  1. $\frac{1}{\mathrm{t}}$
  2. $\frac{2}{\mathrm{t}}$
  3. $\frac{3}{\mathrm{t}}$
  4. $\frac{0.25}{\mathrm{t}}$

Solution

In fundamental mode the length of the closed tube is $\frac{\lambda}{4}$ Time required to travel a distance $\frac{\lambda}{4}$ is $\mathrm{t}$. Hence time required to travel a distance $\lambda$ will be $4 \mathrm{t}$. $\therefore$ Time period $\mathrm{T}=4 \mathrm{t}$ Frequency, $\mathrm{n}=\frac{1}{\mathrm{~T}}=\frac{1}{4 \mathrm{t}}=\frac{0.25}{\mathrm{t}}$

Asked in: MHT CET 2021 (21 Sep Shift 1)

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