7.1 Magnetism

A magnet is an object that produces a magnetic field. This is a region where other magnets or magnetic materials (like iron, steel, nickel, and cobalt) will experience a non-contact force.

All magnets have a North pole and a South pole.

• Like poles repel (North-North, South-South).
• Opposite poles attract (North-South).

We can draw magnetic field lines to show the shape and direction of the field. The lines always point from North to South.

Source: Wikimedia Commons

A permanent magnet (like a bar magnet) has its own field all the time. An induced magnet is a material that becomes a magnet only when it is placed in another magnetic field.

A uniform magnetic field is created by 2 opposite poles. They have the same strength everywhere, and hence the field lines are equally spaced and straight.