Magnetism and Electromagnetism Flashcards
Where on a magnet are the magnetic forces strongest?
At the poles
What happens when two opposite poles are brought together?
They attract
What happens when two like poles are brought together?
They repel
Is magnetism a contact or non-contact force?
Non-contact
What is a permanent magnet?
A material that produces its own magnetic field
What is a temporary magnet?
A material that is only magnetic when placed in a magnetic field, will lose its magnetism when removed
When does a wire generate a magnetic current?
When current is flowing through it
For the right hand rule, what does the thumb represent?
The direction of the current
For the right hand rule, what do the fingers represent?
The direction of the magnetic field
What does the strength of the magnetic field around a wire depend on?
The size of the current, distance from the wire
What is a solenoid?
A coil of wire
What is an electromagnet?
A coil of wire with an iron core
How can an electromagnet be made stronger?
More coils, increased current, soft iron core
What is the motor effect?
When a conductor carrying a current is placed in a magnetic field, the conductor and magnet exert a force on each other
For Fleming’s left hand rule, what does the thumb represent?
The direction of movement/motion
For Fleming’s left hand rule, what does the first finger represent?
The direction of the magnetic field
For Fleming’s left hand rule, what does the second finger represent?
The direction of the current
What equation links current, length, force and magnetic flux?
Force = Magnetic flux x Current x Length
What are the units for magnetic flux?
Tesla, T
What are the units for current?
Amps, A
What are the units for force?
Newtons, N
What is a compass?
A small, suspended bar magnet which points North
What is a compass used for?
Navigation using the Earth’s magnetic field
Why does the Earth have a magnetic field?
The liquid iron and nickel outer core moves around the solid iron and nickel core
What is a pole reversal?
When the location of the magnetic North and South pole are reversed
Where is the magnetic North pole located?
The geographic South pole
Where is the magnetic South pole located?
The geographic North pole
What are the consequences of a pole reversal?
Changes in animal migration, compasses point in the wrong direction
What evidence is there for pole reversals?
Sea floor spreading
What is an electric motor?
A coil or wire rotating within a magnetic field
What is the function of a split ring commutator?
Swaps the direction of the current every half turn to allow 360 degree rotation
How can the speed of an electric motor be increased?
Increase the number of coils, use a stronger magnet, increase the current
What is a magnetic field?
The area around a magnet where the magnetic force can be felt
Name four magnetic materials
Iron, nickel, cobalt, steel
How can you tell the difference between a permanent and a temporary magnet?
Permanent magnets can both attract and repel other magnets, temporary magnets can only attract other magnetic materials
In what direction do magnetic field lines run?
From North to South
