2025 · M/J · 5054/22 | Q4

A sound wave from a vibrating tuning fork is displayed on the oscilloscope shown in Fig. 4.1. The sound wave is detected using a microphone.

(a)Describe the motion of the air particles as the sound wave passes from the tuning fork to the microphone.

Fig. 4.2 shows the trace seen on the oscilloscope when the tuning fork vibrates.

The frequency of the sound is constant.

(b)(i)State what is meant by ‘frequency’.

The trace shown on Fig. 4.2 is produced in 0.050 s.

(b)(ii)Calculate the frequency of the sound wave.

A student near the tuning fork observes the trace and listens to the sound. He notices that the amplitude of the trace decreases.

(b)(iii)State how the sound heard by the student changes.

The tuning fork is replaced by a new tuning fork that produces a sound wave of half the frequency. The controls on the oscilloscope are not changed.

(b)(iv)On Fig. 4.3, draw the trace obtained with the new tuning fork. The trace obtained with the original tuning fork is shown.

Fig. 4.4 shows three adjacent wavefronts of the sound wave as the wavefronts move towards a gap in a wall created by an open door.

Another student, standing at P on the other side of the wall, hears the sound.

(c)(i)On Fig. 4.4, draw the three wavefronts after they pass through the gap.

(c)(ii)State the name of the process involved as the wavefronts pass through the gap and reach P.