Magnetism and Electromagnetism Flashcards
Where are magnetic forces the strongest?
> At the Poles.
What are the connection between unlike and like poles?
> Like poles repel, eating a force of repulsion
Un-like poles attract, creating a fore of attraction
What is a permanent magnet?
> Produces own magnetic field.
What is an induced magnet?
Becomes a magnet when placed in a magnetic field.
Always causes a force of attraction
>If we take away the permanent magnet the induced magnetism will be lost.
How does a compass tell us Earth has its own magnetic field?
> If you hold the compass away from the magnets it always point North-South direction.
What are the 4 magnetic materials?
> Iron
Nickel
Steel
Cobalt
What is a magnetic field?
A magnetic field is the region around a magnet, where it will exhert a force on another magnet or magnetic material.
How can the direction be found with a compass?
1)We place a compass near the north pole
2)Draw a cross at the north pole
3)We now move the compass the south pole of the compass is on the cross
4)Continue this process until we have the magnetic field
5)Connect all dots
> Repeat the whole process from different starting points
What is an Electromagnet?
An electromagnet is a solenoid wrapped around an iron core.
They can be turned on and off
How can you increase the strength of a magnetic field of a electromagnet?
> Larger Current
More closer to wire
More coils of wire
Iron core increases strength
What is a solenoid?
> Coil of Wire
What is the Motor Effect
> When a conductor carrying a current is placed in a magnetic field the magnet producing the field and the conductor exert a force on each other.
What is Flemings Hand Rule show in each finger?
Thumb-Motion
Pointing Finger-Field Strength
Middle Finger-Current
What is the Equation to workout the force in an electromganet?
B x I x L
Magnetic Flux Density x Current x Length
(T) (A) (M)
How does an Electric Motor Work? (4)
> The sides of the coil experience a force
The forces cause moments that act in the same direction.
The moments cause the coil to rotate.
The two halves of the commutator swap from one
brush to the other.
The commutator reverses the current.
Keeping the forces in the same direction
