Zusammenfassung der Ressource
Magnets and Electromagnets
- Definition
- Magnets create a magnetic force between one another and between themselves and magnetic materials.
- Magnetism
- Magnets can attract and repel one another. They also attract magnetic materials.
- Magnetic materials are attracted to magnets but not to each
other. Examples of magnetic materials are; iron, steel and nickel.
- Non-magnetic materials are not affected at all by magnets.
- The magnetic force passes through
non-magnetic materials but not
through magnetic materials.
- The ends of magnets are called
poles. The south-seeking pole
points south and the north
seeking pole points north.
- A north-seeking pole and a
south-seeking pole attract
each other, but two
south-seeking poles or two
north-seeking poles repel
each other.
- Magnetic Field
- The area around magnets is called the magnetic field. Magnetic field lines can be plotted with a compass.
- The direction of the magnetic field goes from the magnet's north pole to its south pole.
- Stronger magnets are represented by showing more lines of force around them.
- The Earth behaves as if it
had a giant magnet inside it.
- The
magnet in a
compass
lines up
with the
Earth's
magnetic
field.
- Own magnet
- You can make your own magnet by stroking an iron nail with one end of a magnet.
- Electromagnet
- When an electric current flows through a wire, the wire behaves like a weak magnet.
- Magnets made using electricity are called electromagnets. These contain a
core, usually of iron, and a coil of wire which carries an electric current.
- Electromagnets are very useful because they can be switched on and off.
- You can change the strength of an electromagnet by changing the size of
the current, coiling the wire or placing a piece of iron inside the coil of wire.
- Relays
- Relay switches use the current from one circuit to switch on the current in another circuit.
- A relay switch has an electromagnet in one circuit next to an iron switch in the other circuit.