Properties of Magnets
- Magnets have two poles: north pole (N) and south pole (S)
- Same poles repel each other, and opposite poles attract each other.
- Magnetically hard materials retain their magnetization once they are magnetized and become permanent magnets. e.g. steel
- Magnetically soft materials lose their magnetization easily. e.g. iron
Magnetic Field Lines
- Magnetic field is space around a magnet where magnetic force can be detected.
- Although actual magnetic field cannot be seen, we can visualize magnetic field with imaginary magnetic field lines.
- Magnetic field lines shows
- the shape of the magnetic field.
- the direction of the magnetic field; magnetic field is directed from the north pole to the south pole.
- the strength of the magnetic field; magnetic field is strong where the field lines are close to each other and weak where the lines are far away from each other.
When two bar magnets of opposing poles are placed closely, the region between the two magnets will experience uniform magnetic field, as shown below. That is, the field lines are parallel to each other.
I. Using iron filings - When you spread iron filings near a magnet, the iron filings line up along the magnetic field line.
II. Using compass - When you place compasses near a magnet, the compass will point in the direction of the magnetic field line.