P7 - Magnetism and Electromagnetism
Simple magnetism Poles and materials Like magnetic poles repel. Unlike poles attract. Magnetic materials can be attracted to a magnet and can become magnetised; non-magnetic materials are not attracted. Soft iron is easy to magnetise and demagnetise. It is used for temporary magnets and electromagnets. Steel is harder to magnetise but keeps its magnetism. It is used for permanent magnets. Induced magnetism occurs when a magnetic material becomes magnetised in an external field. The end nearest a magnet becomes the opposite pole, so the material is attracted. Magnetic fields A magnetic field is a region where a magnetic pole experiences a force. Field direction is the direction of force on a north pole. Around a bar magnet, field lines go from north to south outside the magnet. They never cross. Lines closer together show a stronger field. ...