To determine the strength of the electromagnets, we look at both the current intensity and the number of turns. According to the data provided:
- Electromagnet P: medium current (20 turns)
- Electromagnet Q: low current (20 turns)
- Electromagnet R: low current (15 turns)
Given that a higher current intensity and a higher number of turns both contribute to stronger magnetic forces, we can make the following assessments:
- Electromagnet P has a medium current level but the highest number of turns (20) among those with medium or low current.
- Electromagnet Q has a low current with 20 turns.
- Electromagnet R has a low current with the lowest number of turns (15).
Thus, in order from strongest to weakest magnetic force:
- P (medium current, 20 turns)
- Q (low current, 20 turns)
- R (low current, 15 turns)
The correct order is: P, Q, R.
So the choice is:
P, Q, R