Question

In Kundt's tube experiment wavelength in the metallic rod and air are 80 cm and 16 cm respectively. If the velocity of sound in air is $300m{s}^{-1}$ then the velocity of sound in rod will be

• A. $80m{s}^{-1}$
• B. $3.75m{s}^{-1}$
• C. $240m{s}^{-1}$
• D. $1500m{s}^{-1}$

Answer 1

Answer: (D)

$1500m{s}^{-1}$

Velocity of sound in air $V_{air}=300m{s}^{-1}$, and ${\lambda }_{air}=16cm=0.16m$.

let us say velocity of sound in metal pipe $V_{metal}m{s}^{-1}$, and

${\lambda }_{metal}=80cm=0.8m$.

frequency remain unchanged when medium changes,

$V_{metal}=\frac{{\lambda }_{metal}}{{\lambda }_{air}}{V}_{air}m{s}^{-1}=\left(0.8/0.16\right)\ast 300m{s}^{-1}=1500m{s}^{-1}$.

Option "D" is correct.