Electromagnetism Flashcards
What is electromagnetism?
It’s the link between electricity and magnetism
What do electric currents produce?
Magnetic fields
What do changing magnetic fields produce?
Electric currents
What is real electric current?
The flow of electrons
What is conventional current?
This is the apparent flow of positive charge
What does a circle with a dot in the middle mean?
Conventional current coming out
What does a circle with an X across it mean?
Conventional current is going away from you
What does the right hand grip rule show?
The direction of magnetic field around a conventional current
What is a solenoid?
A loop of wire carrying a current
How would you create an electromagnet?
Put a piece of metal (usually iron) inside a solenoid
The piece of metals magnetic field would move from south to north
How to increase the magnetic field of a solenoid?
Increase the number of coils
Increase the current
Insert a soft iron core
How does a relay work?
Relays use a small current to energise a solenoid to close a switch and turn a large current
What does flemings left hand motor rule show?
Shows the direction of force on a moving positive charge in a magnetic field
Thumb is for force
First finger is for field
Second field is for conventional current
How would you explain flemings left hand motor rule in an exam question?
The magnetic field caused by the current in the conductor interacts with the permanent magnetic field causing a force which accelerates the wire to the left/right.
