At the start, the tube is completely under water. As it is gradually lifted out, its axis stays vertical, as illustrated in Fig. 5.1. While the tube is being raised, a loudspeaker emitting sound of frequency $530\,\text{Hz}$ is placed at the open upper end of the tube. The water level inside the tube always matches the water level outside it. The speed of sound in the air column in the tube is $340\,\text{m s}^{-1}$.
(a)[1]
Describe a simple method by which a student can tell, without any extra apparatus, when a stationary wave has formed in the air column as the tube is raised.
(b)[3]
Determine how high the top end of the tube is above the water surface when the first stationary wave is produced in the tube. Assume that an antinode is located level with the top of the tube.
(c)[1]
Determine how far the tube is moved between the positions where the first and second stationary waves are formed.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “a (much) louder sound is heard” …