IGCSE 0625 · ELECTRICITY & MAGNETISM · 4.1

Simple phenomena of magnetism

Magnetic poles and forces, temporary and permanent magnets, magnetic fields and how we map them, and where magnets are used. It is the foundation for the electromagnetic effects in 4.5.

TOPIC 4.1: SIMPLE PHENOMENA OF MAGNETISM CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 1.5 Forces LEADS TO 4.5 Electromagnetism 4.2 Electricity MAGNETISM & FIELDS 1 · POLES & FORCES Every magnet has a north pole and a south pole. Like poles repel; unlike poles attract. The magnetic force acts without touching. Magnetic materials: iron, steel, cobalt, nickel. S N N S like poles (N–N) repel S N S N unlike poles (N–S) attract 2 · TEMPORARY & PERMANENT A magnetic material near a magnet becomes a magnet itself. This is induced magnetism. Soft iron magnetises and loses it easily: ideal for electromagnet cores. Steel is hard to magnetise but keeps it: ideal for bar magnets and compass needles. N S soft iron clips Remove the magnet and soft iron lets the clips fall. 3 · MAGNETIC FIELDS A magnetic field is the region where a magnet exerts a force. Field lines run from north to south outside the magnet, and never cross. The closer the lines, the stronger the field. A plotting compass shows the direction. S N 4 · USING MAGNETS Magnets and fields are everywhere. A compass needle lines up with Earth's field and points north. Magnetic catches hold doors and fridges shut. Magnets separate steel from other scrap. A current can make a magnet too: the electromagnet leads into Topic 4.5. N
TOPIC 4.1: SIMPLE PHENOMENA OF MAGNETISM CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 1.5 Forces LEADS TO 4.5 Electromagnetism 4.2 Electricity MAGNETISM & FIELDS 1 · POLES & FORCES Every magnet has a north pole and a south pole. Like poles repel; unlike poles attract. The magnetic force acts without touching. Magnetic materials: iron, steel, cobalt, nickel. S N N S like poles (N–N) repel S N S N unlike poles (N–S) attract 2 · TEMPORARY & PERMANENT A magnetic material near a magnet becomes a magnet itself. This is induced magnetism. Soft iron magnetises and loses it easily: ideal for electromagnet cores. Steel is hard to magnetise but keeps it: ideal for bar magnets and compass needles. N S soft iron clips Remove the magnet and soft iron lets the clips fall. 3 · MAGNETIC FIELDS A magnetic field is the region where a magnet exerts a force. Field lines run from north to south outside the magnet, and never cross. The closer the lines, the stronger the field. A plotting compass shows the direction. S N 4 · USING MAGNETS Magnets and fields are everywhere. A compass needle lines up with Earth's field and points north. Magnetic catches hold doors and fridges shut. Magnets separate steel from other scrap. A current can make a magnet too: the electromagnet leads into Topic 4.5. N
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