magnetism and electromagnetism Flashcards
(25 cards)
Where are the magnetic forces the strongest?
At the poles of the magnet.
What happens when we bring 2 magnets close together?
They exert a force on each other
What happens when 2 like poles are close together?
They repel (force of repulsion)
What happens when 2 unlike forces are close together?
They attract (
What does a permanent magnet produce?
it’s own magnetic field
What are induced magnets?
An induced magnet is an object that becomes a magnet when it’s placed in a magnetic field
What do induced magnets always cause?
cause a force of attraction
What are the 4 types of magnetic material?
iron, steel, cobalt, nickel
What is a magnetic field?
A region around a magnet where a force acts on another magnetic or on a magnetic field
What does the strength of a magnetic field depend on?
On the distance from the magnet
What happens when current is flowing through a conducting wire?
A magnetic field is produced around the wire
In a circuit, what does the strength of the magnetic field depend on?
The size of the current and how close it is to the wire
What happens if we change the direction of the current to the magnetic field?
We change the direction of the magnetic field.
what a solenoid?
A coil of wire that produces a magnetic field when current flows through it.
How do we increase the strength of the magnetic field in terms of electromagnetic magnets?
-increase the size of the current
-increase the number of turns of coils
-place a bit of iron in the solenoid then we increase the magnetic field (iron core)
How can we increase the speed of the electric motor?
increase the current
add more turns to the coil
increase the magnetic flux density
What happens when we put a wire flowing with current, in an another magnetic field?
The magnetic field around the wire now interacts with the magnetic field between the magnets causing the wire to now experience a force.
What is magnetic flux density and what is it measured in?
𝐵
B = magnetic field strength (in teslas, T)
What is “I” measured in and what is it?
Current - Amps
When can the motor effect only take place?
When the wire is at right angles to the magnetic field
How can we determine the direction of the force during them motor effect?
Flemings left hand rule
1st - direction of magnetic field
2nd - direction of the conventional current (+ to -)
Thumb - Direction of the force
In motor effect, what happens if the current is parallel to the magnetic field?
Then it will no experience a force.
What is the purpose of the split-ring commutator?
To solve the problem - switch the direction of the current when the loop passes 90 degrees
How is the split-ring commutator structured?
split metal ring with each side connected to conducting brushes (which allow current to pass through)
