Question

A tube closed at one end and containing air produces, when excited, the fundamental note of frequency 512Hz. If the tube is open at both ends, the fundamental frequency that can be excited is (in Hz).

(a) 1024

(b) 512

(c) 256

(d) 128

This question was posed to me at a job interview.

This is a very interesting question from Transverse Waves topic in portion Waves of Engineering Physics I

Answer 1

The correct choice is (a) 1024

For explanation: Fundamental frequency of a closed pipe,

γ=v/4L=512Hz

Fundamental frequency of open pipe

γ^‘=v/4L=2γ=2×512=1024Hz.