Science: Electromagnets Flashcards
What are the two poles of a magnet called?
North and South
What are the 3 magnetic metals?
iron, nickel and cobalt
How are electromagnets made?
by wrapping a coil of wire around a magnetic core
Are electromagnets or permanent magnets stronger?
Electromagnets
3 ways you can increase the strength of an electromagnet:
•Increasing the number of turns on the coil around the core of the electromagnet
•Increasing the current which is flowing through the coil of wire
•Using a more magnetic material for the core, e.g. iron rather than aluminium
What is an area where a magnetic material will experience a force?
Magnetic field
Which direction do magnetic field lines go in?
North Pole of the magnet to south pole
What do close together magnetic field lines mean?
A stronger magnetic field
2 ways you can find out the shape of a magnetic field?
• Using plotting compasses
• Using iron filings
What are circuit breakers + how are electromagnets used as circuit breakers?
Circuit breakers detect large changes in current in a house, and will break a circuit
When a large current flows, the electromagnet becomes strong enough to attract an iron catch which will break a circuit
They can then be reset and used again
This makes them suitable as an electrical safety device in a home
How are electromagnets used as loudspeakers?
Loudspeakers use an electromagnet in order to generate sound
A current passes through the coil and creates an electromagnet, this repels another permanent magnet which moves the cone in and out creating sound
How are electromagnets used in electric bells?
The electromagnet attracts the iron armature
When it moves, it breaks the circuit, no longer allowing current to flow
The coil and core are no longer magnetic meaning the spring is no longer attracted and returns to its original position
The bell is rung once
The circuit is complete again, restarting the process
