P3.3.1 The motor effect Flashcards
What happens when a current is passed through a wire?
A circular magnetic field is produced around the wire.
How would you create an electromagnet?
By wrapping a wire around a soft iron core.
Give an example of where electromagnets are used?
Cranes - to lift and drop iron and steel in scrapyards, recycling centres and steel works.
What is the motor effect?
A coil of wire that is free to rotate between two opposite magnetic poles experiences a force and moves when a current is passed through it.
How do you work out the direction of a current / the direction of a magnetic field?
Right hand rule.
How do you increase the size of the force on the wire in the motor effect?
Increase the strength of the magnetic field.
Increase the size of the current.
What happens when the wire is placed parallel to the direction of the magnetic field?
The wire will not experience any force.
What direction should the wire face to experience the greatest force?
Perpendicular to the direction of the magnetic field.
How do you reverse the direction of the force in the motor effect?
Reverse the direction of the current or the direction of the magnetic field.
How do you work out the direction of the force in the motor effect?
Fleming’s left hand rule.
thuMb – Movement
Forefinger – magnetic Field
seCond finger – Current
How does an electric motor work?
A current is run through a wire, one side running away from the commutator and one side running towards it. This causes one side to move upwards and one side to move downwards.
The commutator reverses the current every half turn which makes sure that the wires always have a current in the correct direction to make the wire continue spinning and not come to a stop.
