A Kundt's tube experiment is conducted with a1m long glass rod , twice , one with air and the other with hydrogen , gas filled in the tube . In the first case , there were 11 heaps of lycopodium powder within a length of 64.4 cm between the first and the last . The corresponding parameters in the second case are5 nodal heaps within99.7 cm length. Find the velocity of sound in glass and in hydrogen m if that in air be 335 m//s.

A Kundt's tube experiment is conducted with a1m long glass rod , twice

1.	A Kundt's tube experiment is conducted with a1m long glass rod , twice , one with air and the other with hydrogen , gas filled in the tube . In the first case , there were 11 heaps of lycopodium powder within a length of 64.4 cm between the first and the last . The corresponding parameters in the second case are5 nodal heaps within99.7 cm length. Find the velocity of sound in glass and in hydrogen m if that in air be 335 m//s.
Answer» Solution :In case of air , distance between TWO CONSECUTIVE nodes (heaps of powder) ` = ( 64.4 cm)/( 10) = 6.44 cm` If ` lambda_(a) and lambda_(r)` be the respective wavelengths of sound in air and in rod , then ` lambda_(a) = 2 xx 6.44 cm and lambda _(r) = 2 xx 100 cm` SINCE the frequency REMAINS the same , so ` f = (v_(a))/( lambda_(a)) = (v_(r))/( lambda_(r))` ` v_(r) = ( lambda_(r))/( lambda_(a)) v_(a) = (( 2 xx 100 cm))/(( 2 xx 6.44 cm)) xx 335 m//s = 5.2 km//s` If ` v_(H) and lambda_(h) ` corresponds to the velocity and the wavelength of sound waves in hydrogen respectively , then ` (v_(a))/( lambda_(a)) = (v_(h))/( lambda_(h)) or v_(h) = ( lambda_(h))/( lambda_(a)) xx v_(a)` `v_(h) = (( 99.7 cm //4))/( 6.44 cm) xx 335 m//s = 1.3 km//s`