Magnetic fields
The region around a magnet where another magnet or a magnetic material feels a force. Field lines run from north to south and are closest where the field is strongest.
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Analogy
Like an invisible web around a magnet.
In practice
A compass needle lines up with the Earth's magnetic field. Iron, steel, nickel and cobalt are magnetic.
Practice
Flashcards
- Do like poles attract or repel?Like poles repel.
Interview questions
- Explain how an electric motor works.
- A current-carrying coil sits in a magnetic field
- Each side of the coil feels an opposite force
- The coil rotates
- A split-ring commutator reverses the current every half turn
Questions people ask
How can I draw a magnetic field?
Draw lines leaving the north pole and entering the south pole, with arrows showing the direction. Draw them closer together where the field is strongest, near the poles. Sprinkled iron filings or a plotting compass can show the pattern around a real magnet.
Do like poles attract or repel?
Like poles repel and unlike poles attract. Two north poles push apart, but a north and a south pole pull together. This is the same pattern as electric charges. You can feel it by trying to push two bar magnets together with the same ends facing.