Unit 3 - (Magnestism) Electromagnetism Flashcards
What are the poles of magnet in terms of magnetism
The parts of the magnet where the magnetism Is the strongest
What is a magnetic field?
Is the space around a magnet where it’s magnetic force acts
What do the lines of magnetic force show?
The shape of the field
Which metal alloys will magnets attract to?
Magnets will ONLY attract to metal alloys which contain: -iron -cobalt -nickel
What is the end of the magnet called which always points north?
The North-seeking pole
What is electromagnetism?
Magnetism produced by electric currents
What is an electromagnet?
A magnet whose magnetic field can be turned on and off with an electric current
Advantages of electromagnets compared with normal magnets?
Can switch them off Can control their strength
What is the composition of an electromagnet?
A solenoid (coil of wire) around an iron core
How to make the magnetic field around an electromagnet stronger?
- More turns in the coil
- Use a larger current
- Put an iron core in the solenoid (compared to eg plastic) 4. Make the turns tighter
What happen if you freely suspend a magnet?
It will always come to rest on the north/south line of the Earth
What happens when a current flows through a wire?
A magnetic field is created around the wire
What is a magnetic field made up from?
Concentric circles with the wire in the centre
What is electromagnetic induction?
The creation of a pd (voltage) across a conductor which is experiencing a change in magnetic field
how can you do electromagnetic iduction?
By moving a magnet in a coil of wire or moving an electrical conductor in a magnetic field (‘cutting’ the magnetic field lines)
What happens t the pd if you move the magnet in the opposite direction?
It The pd/current will be reversed too
What happens to the pd if the polarity of the magnet is reversed?
It will be reversed too
How do Dynamos work?
The cog wheel at the top is positioned so that it touched one of the wheels. As the wheels move rounds, it turns the cog which it attatched to the magnet. This creates an AC current to power the lights
