| Date | May 2015 | Marks available | 3 | Reference code | 15M.3.SL.TZ1.3 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Determine and State | Question number | 3 | Adapted from | N/A |
Question
This question is about the Doppler effect.
The diagram shows wavefronts in air produced by a stationary source S of sound. The distance between successive wavefronts is equal to the wavelength of the sound. The speed of sound is c.
On the diagram, sketch three successive wavefronts produced when S is moving to the left at a speed of 0.5c.
A source of X-rays rotates on a turntable. Radiation of wavelength 7.5 nm is emitted by the source and undergoes a maximum shift of 0.50 fm. The distance between the source and the detector is large in comparison to the diameter of the turntable.
(i) Determine the speed of a point on the edge of the turntable.
(ii) State the assumption you made in your answer to (b)(i).
Markscheme
3 circular wavefronts;
2 centres/sources of wavefronts move left (by one box);
Drawn circular wavefronts may be larger as in diagram here, or could be equal sized. Both are acceptable.
(i) \(v = \frac{{5 \times {{10}^{ - 16}} \times 3 \times {{10}^8}}}{{7.5 \times {{10}^{ - 9}}}}\);
20(ms-1);
Use of sound equation not acceptable.
(ii) assume speed of X-rays \( = \) c / assume speed of turntable << c;
