DP Physics (last assessment 2024)
Question 21M.2.HL.TZ2.b
| Date | May 2021 | Marks available | [Maximum mark: 4] | Reference code | 21M.2.HL.TZ2.b |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 4]
21M.2.HL.TZ2.b
A pendulum with a metal bob comes to rest after 200 swings. The same pendulum, released from the same position, now swings at 90° to the direction of a strong magnetic field and comes to rest after 20 swings.
Explain why the pendulum comes to rest after a smaller number of swings.
[4]
Markscheme
bob cuts mag field lines
OR
there is a change in flux linkage ✓
induced emf across bob ✓
leading to eddy/induced current in bob ✓
eddy/induced current produces a magnetic field that opposes «direction of» motion ✓
force due to the induced magnetic field decelerates bob ✓
damping of pendulum increases/there is additional «magnetic» damping ✓
MP4 and MP5 can be expressed in terms of energy transfer from kinetic energy of bob to electrical/thermal energy in bob
