Magnetism Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

what is a permanent magnet

A

always produce a magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is an induced magnet

A

become magnatised when in another magnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what metals can become magnatised

A

iron
colbolt
nickel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what metals can not become magnatised

A

aluminium and copper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens to a electric current flowing through a wire

A

will produce its own magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the motor effect

A

when a current flowing wire is in another magnetic field it will experience a force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how to calculate force f=bil

A

magnetic flux density(b - tesla) x current x length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what will happen between the forces in an induced magnet and a permanent magnet

A

they will always be attracted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does being magnetically soft mean

A

lose their magnetism really quickly (nickel and iron)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does being magnetically hard mean

A

lose magnetism slowly (steel)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what will the field lines look like in a wire that has a current flowing through it

A

circles closest together near to the wire as that is where the magnetic field is strongest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the right hand rule

A

put right hand into fist where the thumb is pointing up to the current the other fingers will show the direction of the magnetic field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what happens to the magnetic fields in a circular coil

A

they interact and become
stretched out to form ellipses
they then combine and form one magnetic field with a straight line in the middle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is a solenoid

A

wire coiled up into spiral shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the properties of a magnetic field in a solenoid

A

strong
uniform

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

electromagnets are only magnetic when

A

current is flowing through a wire

17
Q

how can we reverse the direction of a electromagnet

A

reverse current

18
Q

what are 4 ways to increase the strength of an electromagnet

A

increase current
increase number of coils (length the same)
decrease length(coils the same)
add iron core to solenoid

19
Q

why does decreasing the length of a solenoid and increasing the number of coils increase the strength of a electromagnet

A

densely packed coils

20
Q

why does adding an iron core increase the strength of a electromagnet

A

as iron is an induced magnet it will increase the magnetic field strength

21
Q

to experience a full force the wire has to be

A

90 degrees to the magnetic field

22
Q

to experience a slight force the wire has to be

A

at an angle

23
Q

to experience no force the wire has to be

A

same direction as the magnetic field

24
Q

what happens to a coil in an electric motor

A

spin 180 and the positive and negative terminals will be switched and also the forces will be switched and the coil will flip back to where it has started

25
Q

what do we have to do to make sure an electric motor turns 360 degrees

A

change the direction of the current every half turn

26
Q

how do we make sure an electric motor turns 360 degrees

A

split ring commutator

27
Q

what does a split ring commutator do

A

swaps the positive and negative connections every half turn
so the direction of current also swaps
so forces acting on the coil will always be the same

28
Q

how can we increase the speed of rotations in an electric motor

A

current
add more turns to coil
increase magnetic flux density(adding stronger magnets)