DP Physics (last assessment 2024)
Question 19M.3.SL.TZ2.b
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.3.SL.TZ2.b |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
19M.3.SL.TZ2.b
Two protons are moving to the right with the same speed v with respect to an observer at rest in the laboratory frame.
Explain why there is no magnetic force on each proton in its own rest frame.
[1]
Markscheme
protons at rest produce no magnetic field
OR
mention of F = Bev where B and/or v =0 ✔
Examiners report
Candidates usually realised that the magnetic field was due to the motion of the protons and that in the proton rest frame there could be no magnetic field. The answers were too often poorly worded and the candidates appeared to reword the question without providing a clear explanation.
