P13 Electromagnetism
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What are the four magnetic materials
Iron, steel, nickel, cobalt
What is a magnetic field
The region where around a magnet where a force acts on another magnetic material
Where are magnetic field lines most concentrated
At the poles
How do you magnetise a magnetic material
By placing it in a magnetic field Which is said to INDUCE MAGNETISM
What does the earths magnetic field have a similar pattern to
A bar magnet
What happens to a wire when an electric current passes along it
A magnetic field is set up
How can you use your right hand grip rule to find the current
If the current faces the same way as your thumb Then your fingers point the direction of the magnetic field
What is a solenoid
A long coil of insulated wire Which produces a stronger magnetic field then a straight wire becuase each coil has its own magnetic field Each magnetic field combines to form a much stronger magnetic field
How can a magnetic field around a solenoid change
The current is increased The number of coils is increased Reverses its direction if the current is reversed
What do the magnetic lines inside the solenoid do
Be parallel to the axis of the solenoid and are all in the same direction
How is the magnetic field outside a solenoid
It is similar to a bar magnet however each field line is a complete loop because it passes through the inside of the solenoid
What is an electromagnet
A solenoid which is wrapped around an iron bar When a current passes along the wire the magnetic field of the wire magnetises the iron bar increasing the strength of the magnetic field
What is the motor effect
A force can act on a wire in a magnetic field when a current is passed through the wire
What can you use Flemings left hand rule for
To determine the direction of the force acting on a conductor in a magnetic field.
What is flemings left hand rule
Using your left hand point point your thumb and the next to finger at right hands to each other Point your thumb outwards representing force Point your pointing finger straight (First 90 degree angle) this represents the field And point your middle finger downwards representing current (Second 90 degree angle between pointing and middle finger) Use each finger to work out one of the missing parts direction on where it is moving the wire
What is the magnetic flux density
The measure of the strength of the magnetic field Symbol B measured in Tesla,T
When a current passes through a coil the coil turns because
It is in uniform with the magnetic field The current on each side of the coil is in opposite directions.This means that each side of the coil feels a force in opposite directions making the coil rotate