VISUAL PHYSICS ONLINE

3.1 WAVES

P31 003

The following is a multiple choice question from a past HSC Physics Examination Paper. However, the question has two possible correct answers. The question is really not sensible. Rewrite it so that it is a sensible physics question, and then give your answer.

A tuning fork sets the air column in an open tube resonating at its fundamental frequency as shown.

The points X and Y represent respectively, the positions of

(A) antinode, antinode

(B) antinode, node

(C) node, antinode

(D) node, node

View solution below only after you have completed the answering the question.

Solution

The standing wave setup in the tube can be described in terms of the pressure fluctuations around atmospheric pressure or the longitudinal particle displacements of the air molecules. The question does not state whether the nodes (N) or antinodes (A) correspond to pressure or particle displacement.

Review: Standing waves and normal modes for vibrating air columns