Question 19M.2.HL.TZ2.10
| Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.2.HL.TZ2.10 |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | Deduce, Sketch, State | Question number | 10 | Adapted from | N/A |
A small magnet is dropped from rest above a stationary horizontal conducting ring. The south (S) pole of the magnet is upwards.
While the magnet is moving towards the ring, state why the magnetic flux in the ring is increasing.
[1]
the magnetic field at the position of the ring is increasing «because the magnet gets closer to the ring» ✔
This was well-answered.
While the magnet is moving towards the ring, sketch, using an arrow on Diagram 2, the direction of the induced current in the ring.
[1]
the current must be counterclockwise «in diagram 2» ✔
eg:
Answers here were reasonably evenly split between clockwise and anti-clockwise, with the odd few arrows pointing left or right.
While the magnet is moving towards the ring, deduce the direction of the magnetic force on the magnet.
[2]
since the induced magnetic field is upwards
OR
by Lenz law the change «of magnetic field/flux» must be opposed
OR
by conservation of energy the movement of the magnet must be opposed ✔
therefore the force is repulsive/upwards ✔
The majority of candidates recognised that the magnetic force would be upwards and the most common way of explaining this was via Lenz’s law. Students needed to get across that the force is opposing a change or a motion.