Magnets and Electromagnets Flashcards
what is a magnetic force?
it exists between two magnets and between a magnet and any magnetic material. this can be a push or a pull.
what are magnets?
these most commonly contain iron and attract and repel each other. they also attract magnetic materials.
what are magnetic materials?
these include: IRON, STEEL, NICKEL, COBAL
they are attracted to magnets, but not EACH OTHER.
what are non magnetic materials?
these are not affected by magnets. non metals and some metals such as COPPER and ALUMINIUM, are examples of non magnetic materials
what do magnetic materials NOT let pass through?
magnetic forces
what are a magnets poles called?
north seeking and south seeking
what are the rules of magnetic poles
like poles repel
unlike poles attract
how can you tell if a magnet is strong or weak?
where the magnetic force is stronger, there are more field lines.
how can you make a magnet?
stroke an iron nail several times with one end of a magnet. all the particles in the nail will line up in the direction of the stroke, making it temporarily magnetic.
why are electromagnets useful?
they can be switched on an off
-you can control their strength
how to make an electromagnet stronger?
- increase current
- wind wire into a coil
- place a core into the coil (iron)
how do doorbells use electromagnets?
the electromagnet attratc a springy metal strip holding the hammer
when the hammer moves and hits the gong, it breaks the circuit. the current stops flowing and the electromagnet turns off and the metal strip moved back.
how do relays use electromagnets?
when the first circuit is switched on, the electromagnet becomes magnetised, attracting the iron switch in the other circuit. the movement of the armature completes the second circuit and allows a current to flow in it.
why is a relay switch used in a car motor?
it is a safe way to start a large current
