| Date | May 2012 | Marks available | 3 | Reference code | 12M.3.SL.TZ1.2 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Calculate, Explain, Label, Sketch, and State | Question number | 2 | Adapted from | N/A |
Question
This question is about standing waves on strings.
A string is fixed at one end and the other free end is moved up and down. Explain how a standing wave can be formed on the string.
The diagram shows a string vibrating in its first harmonic mode. Both ends
of the string are fixed.
(i) Label an antinode on the diagram.
(ii) The length of the string is 0.85 m and its first harmonic frequency is 73 Hz. Calculate the speed of the waves on the string.
(iii) Sketch how the string will appear if it is vibrated at a frequency three times that of the first harmonic frequency.
(iv) State the speed of the wave when the string is vibrated at a frequency three times that of the first harmonic frequency.
Markscheme
at certain fixed frequencies;
incident wave and reflected wave;
superpose (or interfere);
(i) antinode clearly labelled in centre;
(ii) wavelength=1.7 m;
speed=1.2×102 ms-1;
(iii) 
(iv) 1.2×102 ms-1;
