Which Magnetic Pole?
About
This simulation models a classic magnetic poles identification experiment. A bar magnet with known pole labels (N and S) slides horizontally across the top of the scene using the left and right arrow keys. Below it, two bar magnets are mounted on pivot pins so they can rotate freely around their centers. As the known magnet passes over each pivot, the unknown magnets swing to align with the magnetic field — their ends are pulled or pushed by the known magnet according to the rules of magnetic attraction and repulsion.
By watching which end of each unknown magnet points toward the N end of the known magnet, students can identify that end as S — because opposite poles attract. The end that swings away must be N, since like poles repel. The effect is most dramatic when the known magnet is directly above a pivot point, causing the unknown magnet to snap to a near-vertical alignment. Sliding the known magnet from one side of a pivot to the other reverses the angle, demonstrating the continuous nature of the magnetic field.
Learning Goals
- Identify which end of an unknown magnet is N and which is S, based on how it responds to a known magnet
- State the rule: opposite poles attract and like poles repel
- Explain why each unknown magnet rotates as the known magnet moves past it, and predict the direction of rotation
- Describe what happens to the unknown magnets when the known magnet is directly above each pivot point
How to Use
- Press and hold the left or right arrow key to slide the known magnet across the top of the canvas
- Observe how each unknown magnet rotates as the known magnet approaches, passes over, and moves away from its pivot point
- Identify which end of each unknown magnet is S — it is the end that points toward the N end of the known magnet
- Verify your identification by sliding the known magnet to the opposite side: the S end should follow the N end as it passes over the pivot