Lesson 12 of 14
The big picture
Show on a big screenThis table sums up the chapter.
| Idea | The key line |
|---|---|
| Field of a wire | Rings round the wire. Thumb on the current, fingers on the field. |
| Field lines | N to S outside a magnet. Closer means stronger. Never cross. |
| Coil | More turns or more current gives a stronger field. |
| Force on a wire | Left-hand rule: field, current, push. |
| House circuit | Fuse on the live wire. Appliances in parallel. Earth for faults. |
| AC and DC | AC reverses twice a cycle. Indian supply: 50 Hz. |
| Motor | Current in, motion out. A split ring reverses the current every half turn. |
| Field of a loop | One way through the loop. In its plane, the other way outside. Right hand: fingers with the current, thumb with the field. |
| Generator | Motion in, current out. A moving magnet near a coil induces a current. |
| Wire colours | Your book: red, black, green. A cord may use brown, blue. Often two circuits: 5 A, 15 A. |
A compass turns near a current. A current makes a field. Coil magnets and motors use that fact. Generators use the reverse.
Read Chapter 12, Magnetic Effects of Electric Current, in your book. Try its exercises. Our Environment is next.