Waves

JEE Main level, numerical answer, medium

92 of 142

Question 92 of 142

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 20.0cm20.0cm for a tuning fork of frequency 400Hz400Hz is used. The velocity of the sound at room temperature is 336ms−1336{ms}^{-1}. The third resonance is observed when the air column has a length of _____ cmcm

Show answer and solution

Answer: 104

Wavelength of wave ⇒λ=vf=336400=84cm\Rightarrow \lambda =\dfrac{v}{f}=\dfrac{336}{400}=84cm
At first resonance
λ4=l+e⇒844=20+e\dfrac{\lambda }{4}=l+e\Rightarrow \dfrac{84}{4}=20+e, where, ee is end correction.
⇒e=1\Rightarrow e=1
So third resonance length
5λ4=l2+e5\dfrac{\lambda }{4}={l}_{2}+e
5(21)=l2+15\left(21\right)={l}_{2}+1
l2=104cm{l}_{2}=104cm

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Standing waves on a string simulationDrag the sliders and watch the numbers in this question change.

More Physics practice

JEE Main Physics practice question on Waves (Organ Pipe (Vibration of Air Column)), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.