Magnets and Magnetic Materials
Simple Explanation
A magnet has two poles — north (N) and south (S) — and always attracts certain materials toward these poles. Like poles (N-N or S-S) repel each other; unlike poles (N-S) attract. Only a few materials — mainly iron, nickel, and cobalt (and their alloys, like steel) — are strongly attracted to a magnet; these are called ferromagnetic materials. Most other materials (wood, plastic, copper, aluminium) are not magnetic at all.
Why Do We Need It?
The simple rule "like poles repel, unlike poles attract" is the foundation for understanding compasses, magnetic separators used in recycling, and every device built from permanent magnets.
Worked Example
Predict the interaction between two magnets
Two bar magnets are brought together with their north poles facing each other. Predict what happens.
Why Does This Work?
This behavior reflects the underlying magnetic field each pole creates — field lines leave a north pole and enter a south pole, and two overlapping fields either reinforce each other's push (like poles) or pull together to complete the field pattern smoothly (unlike poles).
Real-Life Example
Magnetic separators in recycling plants
Recycling facilities use powerful magnets on conveyor belts to automatically pull out steel and iron cans from a mixed stream of waste.
Since steel and iron are ferromagnetic (strongly attracted to a magnet) while aluminium, plastic, and glass are not, a magnet can sort them automatically without needing to sort by hand.
Practice
Which of these materials is strongly attracted to a magnet?
EasyCommon mistake
Assuming ALL metals are magnetic — most metals (aluminium, copper, gold, silver) are NOT attracted to a magnet at all; only iron, nickel, cobalt, and their alloys are ferromagnetic.
Quick Review
- Like poles repel; unlike poles attract.
- Ferromagnetic materials (iron, nickel, cobalt) are strongly attracted to a magnet.
- Most materials (wood, plastic, copper, aluminium) are not magnetic at all.