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JEE Main 2022 (29 Jun, Shift 2) · Organ Pipes & Resonance Tube

Organ Pipes & Resonance Tube question from JEE Main 2022 (29 Jun, Shift 2)

Q77JEE Main 2022 · 29 JUN · SHIFT 2Medium

Organ Pipes & Resonance Tube

In an experiment to determine the velocity of sound in air at room temperature using a resonance tube, the first resonance is observed when the air column has a length of 20.0 cm for a tuning fork of frequency 400 Hz is used. The velocity of the sound at room temperature is 336 ms−1{}^{-1}. The third resonance is observed when the air column has a length of _____________ cm.

Numerical answer type. Work it out, then open the answer.

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Answer: 104

  1. λ=336400=0.84\lambda = \frac{336}{400} = 0.84 m =84= 84 cm, so λ4=21\frac{\lambda}{4} = 21 cm.
  2. First resonance: 20+e=21⇒e=120 + e = 21 \Rightarrow e = 1 cm.
  3. Third resonance: l3=5λ4−e=105−1=104l_3 = \frac{5\lambda}{4} - e = 105 - 1 = 104 cm
  4. So the answer is 104 cm.
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