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A Physics Mock Study pt2 > Magnetism and Electromagnetism > Flashcards

Magnetism and Electromagnetism Flashcards

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1
Q

how many poles do magnets have? and what are they?

A

they have two poles, north and south

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2
Q

what is a magnetic field?

A

where magnetic materials experiences a force

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3
Q

what are magnetic field lines used for?

A

to show the size and direction of magnetic fields

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4
Q

where do magnetic field lines usually point to?

A

they always point from north to south

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5
Q

what happens if you place the north and south poles of two permanent bar magnets near each other?

A

it creates a uniform field between the two magnets

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6
Q

describe what a uniform field looks like

A

handmade flashcard 14

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7
Q

describe what magnetic field lines looks like

A

handmade flashcard 15

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8
Q

what do magnetics produce?

A

a magnetic field

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9
Q

how can you see magnetic field patterns?

A

by using a compass

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10
Q

why can you see magnetic field patterns with compasses and iron fillings?

A

because they align themselves with magnetic fields

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11
Q

how can you see magnetic fields coming out of a bar of magnets?

A

by using multiple compasses

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12
Q

describe how magnetic fields look like coming out of a magnet bar

A

handmade flashcard 16

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13
Q

what do magnets affect?

A

they affect magnetic materials and other magnets

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14
Q

what do similar poles do with each other?

A

they repel each other

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15
Q

what do opposite poles do with each other?

A

they attract each other

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16
Q

describe how poles repealing each other looks like

A

handmade flashcard 17

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17
Q

describe how poles attracting each other looks like

A

handmade flashcard 18

18
Q

what do poles attract?

A

they attract magnetic materials (that aren’t magnets)

19
Q

what happens when magnetic materials are brought near to a magnet’s magnetic field?

A

that materials acts as a magnet

20
Q

why does a magnetic material acts as a magnet when it is brought close to a magnet?

A

because this magnetism has been induced by the original magnet

21
Q

what happens with the closer the magnet and the magnetic material get with each other?

A

the stronger the induced magnetism will be

22
Q

what happens when an electric current flows?

A

it produces a magnetic field

23
Q

what does an electric current in a conductor produce?

A

it produces a magnetic field around it

24
Q

what does the direction of the magnetic field depend on?

A

on the direction of the current

25
Q

how will the size of the electric current affect the magnetic field?

A

if the electric current is larger the magnetic field will be stronger
if the electric current is smaller the magnetic field will be weaker

26
Q

what causes a magnetic material be considered as soft?

A

if it loses its induced magnetism quickly

27
Q

what causes a magnetic material be considered as hard?

A

if it keeps its induced magnetism permanently

28
Q

what is an example of a soft magnetic material?

A

iron

29
Q

what is an example of a hard magnetic material?

A

steel

30
Q

how can you increase the strength of a magnetic field around a solenoid?

A

by adding a magnetically “soft” iron core through the middle of the coil

31
Q

what is the motor effect?

A

it is when a current-carrying wire is put between magnetic poles, the two magnetic fields affect one another. The result is a force on the wire. This can cause the wire to move

32
Q

what do electric motors use to get them moving?

A

the motor effect

33
Q

what are 4 factors that will speed up an electric motor?

A
  • more current
  • more turns on the coil
  • stronger magnetic field
  • a soft iron core in the coil
34
Q

how do loudspeakers work?

A

using the motor effect

35
Q

describe with detail how a speaker works

there are 3 steps

A

1) the a.c. electrical signals from an amplifier are fed to a coil of wire in the speaker, which is wrapped around the base of a cone
2) the coil is surrounded by a permanent magnet, so the a.c. signals cause a force on the coil and make it move back and fourth
3) these movements make the cone vibrate and this creates sound

36
Q

how is the Fleming’s left hand rule?

A

using your left hand, point your First finger in the direction of the Field and your seCond finger in the direction of the Current. Your thuMb will then point in the direction of the force (Motion)

37
Q

what is electromagnetic induction?

A

the creation of a voltage (and maybe current) in a wire which is experiencing a change in magnetic field

38
Q

what is the dynamo effect?

A

when electromagnetic induction is used to generate electricity using energy from kinetic energy stores

39
Q

what are two different situation where you get electromagnetic induction?

A

a) when an electrical conductor moves through a magnetic field
b) when the magnetic field through an electrical conductor changes

40
Q

what do you need to do to get a bigger voltage?

A

you need to increase…

  • the strength of the magnet
  • the number of turns on the coil
  • the speed of movement
41
Q

how can you test the magnitude and direction of the induced current?

A

you can test it by connecting an ammeter to a conductor and moving the conductor through a magnetic field (or moving a magnetic through the conductor)

42
Q

how does a generator work?

there are 6 points that need to be made

A

1) generators rotate a coil in the magnetic field
2) their construction is pretty much like a motor
3) as the coil spins, a current is induced in the coil. This current changes direction every half turn
4) instead of a split-ring commutator, a.c. generators have slip rings and brushes so the contact s don’t swap every half turn
5) this means they produce a.c. voltage. The faster revolutions produce not only peaks but higher overall voltage too
6) power stations use a.c. generators to produce electricity, they get the energy needed to turn the coil or magnetic field in different ways

A Physics Mock Study pt2 (8 decks)

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