Question 22M.2.SL.TZ1.3b
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.SL.TZ1.3b |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Explain, State | Question number | b | Adapted from | N/A |
Two loudspeakers A and B are initially equidistant from a microphone M. The frequency and intensity emitted by A and B are the same. A and B emit sound in phase. A is fixed in position.
B is moved slowly away from M along the line MP. The graph shows the variation with distance travelled by B of the received intensity at M.
State and explain the wavelength of the sound measured at M.
[2]
wavelength = 26 cm ✓
peak to peak distance is the path difference which is one wavelength
OR
this is the distance B moves to be back in phase «with A» ✓
Allow 25 − 27 cm for MP1.
Many candidates recognized that the wavelength was 26 cm, but the explanations were lacking the details about what information the graph was actually providing. Examiners were looking for a connection back to path difference, and not simply a description of peak-to-peak distance on the graph. Some candidates did not state a wavelength at all, and instead simply discussed the concept of wavelength or suggested that the wavelength was constant.
