Permanent and Induced Magnetism, Magnetic Forces and Fields

This section explains permanent and induced magnetism, magnetic forces and fields covering, poles of a magnet, permanent magnetism versus induced magnetism and compasses and how they work. 

Poles of a Magnet

Magnets have two poles:

• North Pole (N)
• South Pole (S)

Attraction and Repulsion Between Poles

• Opposite poles attract: A north pole and a south pole will pull towards each other.
• Like poles repel: Two north poles or two south poles will push away from each other.

Image

This force of attraction or repulsion is a non-contact force, meaning magnets do not need to be touching to experience these forces.

Permanent Magnetism Versus Induced Magnetism

Permanent Magnets

• Produce their own magnetic field all the time.
• Examples: Bar magnets, fridge magnets.
• Made from magnetic materials like iron, cobalt, nickel, or steel (a mixture of iron and carbon).

Induced Magnets

• Not normally magnetic but can become magnetised when placed in a magnetic field.
• Only remain magnetic while in the field—lose magnetism when removed.
• Examples: Paperclips, iron nails.

Key difference: Permanent magnets always produce a magnetic field, but induced magnets only do so when in the presence of a permanent magnet.

Magnetic Field

A magnetic field is the region around a magnet where a magnetic force can be felt.

• Magnetic fields are strongest at the poles.
• The field gets weaker the further away from the magnet.
• The direction of a magnetic field is always from north to south.

Drawing Magnetic Field Lines

• Magnetic field lines never cross.
• The closer together the lines, the stronger the field.
• The field around a bar magnet forms a pattern where lines leave the north pole and curve around to enter the south pole.

Compasses and How They Work

A compass is a small, freely moving magnet that aligns with the Earth’s magnetic field.

Image

How a Compass Works:

A compass needle is a tiny bar magnet.

The north pole of the needle is attracted to the Earth’s south magnetic pole, which is near the geographic North Pole.

This causes the needle to always point towards the Earth’s North Pole.

Using a Compass to Show Magnetic Fields

• When placed near a bar magnet, the compass needle aligns with the magnet’s field lines.
• By moving the compass around the magnet, you can trace out the shape of the magnetic field.

This guide covers magnetism, magnetic forces, and fields, explaining how magnets interact, the difference between permanent and induced magnetism, and how compasses help us understand magnetic fields.