Question

A Kundt's tube apparatus has a copper rod of length 1.0 m clamped at 25 cm from one of the ends. The tube contains air in which the speed of sound is 340 m s−1. The powder collects in heaps separated by a distance of 5.0 cm. Find the speed of sound waves in copper.

Answer 1

Speed of sound in air vair = 340 ms−1

Velocity of sound in Kundt's tube vrod = ?

Length at which copper rod is clamped l = 25 cm = 25×10−2 m

Distance between the heaps ∆l = 5 cm = 5×10−2 m

vrodvair=2l∆l⇒vrod = 2l∆l×vairOn substituting the respective values in the above equation, we get: vrod=340×25×10−2×25×10−2⇒ vrod=3400 m/s