Available practice: 4 of 30 marks. Scores cover available parts only. Selected question 2 only: oscilloscope and sound-speed practice (4 of 30 marks). The 60-minute duration belongs to the full source paper.
(a)
A student investigates the speed of sound v in air using an oscilloscope.
He uses the apparatus shown in Fig. 2.1.
The balloon and the two microphones are in a straight line. The student uses a pin to burst the balloon, creating a loud sound. The sound is detected first by the microphone at A and then by the microphone at B. The corresponding traces on the screen of the oscilloscope are shown in Fig. 2.2.
The timebase on the oscilloscope is set to 0.50 ms / division.
Use Fig. 2.2 to calculate the time for the sound to travel from A to B.
time = ................................................... ms
Answer guidance
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
[1 mark]
(b)
The student uses an old metre rule to find the distance between A and B. Fig. 2.3 shows the position of A and of B on the metre rule, a distance of 82 cm apart.
Suggest a reason why the student did not place microphone A at the 0.0 cm mark on this metre rule.
Answer guidance
Suggest More than one answer may be acceptable, so long as it is consistent with the physics.
[1 mark]
(c)
Use the equation
to calculate the speed v of sound.
v = .................................................. m / s
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[1 mark]
(d)
Suggest one way in which the student can obtain a more accurate value for v using the same apparatus.
Answer guidance
Suggest More than one answer may be acceptable, so long as it is consistent with the physics.
[1 mark]
5054/41/M/J/19Cambridge O Level Physics 5054 · May/June 2019 · Paper 4 variant 1 · Question 2