question_answer

A glass rod 20 cm long is clamped at the middle. It is set into the longitudinal vibration. If the emitted sound frequency is 4000 Hz, the velocity of sound in glass will be

A) 2800 m/s          

B)        3200 m/s

C) 1600 m/s          

D)        2000 m/s

Correct Answer: C

Solution :

[c] The length of the rod (L), \[=0.2=\frac{\lambda }{2}\]\[\Rightarrow \]\[\lambda =0.4\,m\] \[\therefore \] the velocity of the sound in gas (v), \[=v\times \lambda =4000\times 0.4=1600\,m/s\]