MediumPhysicsHigh School (9–10)Electricity & Magnetism › Magnetic Effects of CurrentConceptualBoard Exam
A bar magnet 12 cm long is cut into three equal pieces…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A bar magnet long is cut into three equal pieces. How long is each piece? How many poles does each piece have, and how many poles are there in all? Can we get a north pole on its own this way?
Need a reminder? The key ideaShow
Every magnet has a north pole and a south pole. Like poles repel and unlike poles attract. A magnet attracts iron, nickel and cobalt, but not copper, aluminium or plastic. A piece of a magnet is a whole magnet, with two poles.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The pieces. each.
Step 2. The poles. Each piece is a complete magnet: new poles appear at every cut. So each piece has poles, and there are poles in all.
Answer: pieces, poles each, poles in all. A north pole on its own cannot be made: however small the piece, it has two poles.
Check. Each cut makes two new poles, one on each side: cuts give new poles, and with the old poles that makes poles.
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