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PHYSICS GCSE > ELECTROMAGNETISM > Flashcards

ELECTROMAGNETISM Flashcards

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1
Q

what do the magnets produce

A

magnetic fields

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2
Q

what is a permanent magnet

A

permanent magnets produce their own magnetic field and the magnetic field cannot be turned on and off

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3
Q

what is an induced magnet

A

they are magnetic materials that turn into a magnet when theyre put into an magnetic field

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4
Q

the force between the permanent and induced magnets is always

A

attractive

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5
Q

what happens when you take away the magnetic field from induced magnets

A

the induced magnets quickly lose their magnetism and stop producing a magnetic field

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6
Q

give two differences between permanent and induced magnets

A

permanent magnets produce their own magnetic field
induced magnets become magnets when put in an magnetic field
the force between permanent and induced magnets is always attractive
the force between two permanent magnets can be attractive or repulsive

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7
Q

the force between two permanent magnets can be

A

attractive or repulsive

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8
Q

when a current flows through a wire

A

a magnetic field is created around the wire

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9
Q

what is a solenoid

A

it is a coil of wire

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10
Q

electromagnets can be

A

turned on and turned off

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11
Q

How can the motor effect happen

A

It happens when you put a current carrying wire in a magnetic field
This causes the magnet and the conductor to exert a force on each other

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12
Q

What three things does the force acting on a conductor in a magnetic field depend on

A

Magnetic flux density
Size of the current
The length of the conductor that’s in the magnetic field

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13
Q

How do you find the direction of the force

A

Flemings left hand rule

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14
Q

What does your index finger represent in Flemings left hand run

A

Direction of

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15
Q

What does your middle finger mean in Flemings

A

The direction of the current

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16
Q

Force=…. (electromagnetism)

A

F=BIL

FORCE=MAGNETIC FLUX DENSITYCURRENTLENGTH

17
Q

Units for F=BIL

A

(F)FORCE= N
(B)MAGNETIC FLUX DENSITY= T-Tesla
(I)CURRENT=A
(L)LENGTH= M

18
Q

how does a loudspeaker convert electrical signals into sound waves

A

a coil of wire carrying an alternating current is wrapped around a pole of a permanent magnet which is surrounded by the other pole
when a current flows through the wire this causes a force which moves the cone in one direction
when the current reverses the force is reversed and the cone is moved in the opposite direction
this makes the cone vibrate which vibrates the air around it to create a sound wave of the same frequency as the alternating current

19
Q

generator effect

A

using a mag field and a force on a wire to produce a current

20
Q

what are generators Generators rotate a coil…..

A

generators rotate a coil in a magnetic field
as the coil spins a current is induced in the coil, this current changes direction every half turn
they have slip rings and brushes so the contacts don’t swap every half turn
so they produce an alternating current

21
Q

dynamos

A

work in the same way as generators but they have split ring commutators
this swaps the connection every half turn to keep current flowing in the same direction

22
Q

what are transformers

A

transformers change the size of the potential difference of an alternating current
they have two coils of wire a primary and secondary coil joined with an iron core

23
Q

what is a step up transformer

A

step the potential difference up, they have more turns on the secondary coil than the primary coil

24
Q

what is a step down transformer

A

step the potential difference down,

they have more turns on the primary coil than the secondary coil

25
Q

equations for transformers

A

Vp/Vs=Np/Ns
input pd/output pd=no of turns on primary coil/no of turns in secondary coil

VsIs=VpIp
Pd across secondary coilcurrent thru sec coil= pd across prim coil current thru prim coil

26
Q

how do you make an electromagnet stronger

A

more current
more coils
add a soft iron core

27
Q

how do you make the motor affect larger

A

more current
stronger magnet
use more wire (more coils)

28
Q

how do you make the generator effect larger

A

bigger force eg move wire faster
stronger magnet
more coils

29
Q

types of electromagnets

A

scrapyard crane
relay switch
electric bell

30
Q

motor effect example

A

a motor

31
Q

generator effect examples

A

dynamo and alternator

32
Q

combination of m and g effect

A

microphone-sound—electrical (motor effect)]
loudspeaker- electrical—sound (generator effect)
transformers

33
Q

is an alternator AC or DC

A

AC

34
Q

is an dynamo AC or DC

A

DC

35
Q

a split ring commutator turns….

A

DC to AC

36
Q

examples of permanent magnets

A

horseshoe magnet

bar magnet

37
Q

detecting magnetic fields

A

place the plotting compass near the magnet on a piece of paper
mark the direction the compass needle points
move the plotting compass to many different positions in the magnetic field, marking the needle direction each time
join the points to show the field lines

PHYSICS GCSE (12 decks)

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