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P3 > Electromagnetism > Flashcards

Electromagnetism Flashcards

1
Q

What is a magnetic field?

A

A region where magnetic materials feel a force

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2
Q

2 things a magnetic field can be created by

A
  • Magnets

- Current flowing in a wire

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3
Q

3 ways to increase the size of the force on the wire

A
  • Increase the current
  • Increase the magnetic field strength
  • Increase the number of wires in the field
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4
Q

What is the Motor Effect?

A

Force produced on a wire is used to create movement (rotational)

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5
Q

How can you predict the direction of the force produced on a wire?

A

Fleming’s Left Hand Rule

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6
Q

What is Electromagnetic Induction?

A

Electricity is induced (created) when a wire cuts through magnetic field lines

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7
Q

In generators, the output voltage/current is proportional to

A

1) the speed of rotation

2) the number of turns on the coil

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8
Q

The output voltage/current in a generator can be increased if…

A

The magnetic field strength increases

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9
Q

How can the direction of the induced current in a generator be predicted?

A

Fleming’s Right Hand Rule

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10
Q

How is electricity created in the second coil? (QWC)

A
  • The alternating current in the primary coil creates a changing magnetic field around it
  • Iron is a magnetic material and so easily transmits this magnetic field to the secondary coil
  • The constantly changing magnetic field around the secondary coil induces a voltage in this coil
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11
Q

What is magnetism?

A

Physical phenomenon produced by motion of electric charge which results in attractive and repulsive forces between objects

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12
Q

What will happen when the north pole of a magnet and a south pole of a magnet are pushed towards each other?

A

They will attract

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13
Q

What will happen when 2 north poles of a magnet or 2 south poles of a magnet are pushed towards each other?

A

They will repel

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14
Q

Field line rules

A
  • Show shape of magnetic field
  • Direction of field lines (North to South)
  • Strength of magnetic field (Closer together = stronger)
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15
Q

Magnetic materials

A

-Steel/Iron
-Cobalt
-Nickel
(Remember SINC)

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16
Q

How can magnetism be induced in magnetic materials?

A
  • Placing in magnetic field

- Stroking them with another magnet

17
Q

What is the difference between magnetically soft and magnetically hard materials?

A

Soft:
-Gain and lose electrons easily
Hard:
-Harder to magnetise but retain their magnetism

18
Q

What is an electromagnet?

A

Magnet that can be turned on and off by flow of electricity

19
Q

What is a solenoid?

A

Electromagnetic with many coils

20
Q

What can a solenoid be used for?

A

Can be used as electromagnets, inductors in electric circuits and as miniature wireless receiving antennas

21
Q

What happens when 2 magnetic fields interact?

A

They attract or repel

22
Q

What happens when a current carrying wire passes through a magnetic field provided by 2 bar magnets?

A

Direction of induced current reversed if wire is moved in opposite direction or field reversed

23
Q

How can you increase force experienced by metal conductor (wire)?

A
  • Increase speed of movement

- Increase magnet strength

24
Q

What is the role of a commentator in a motor?

A

Ensure current always flows in same direction

25
Q

Uses for Motor Effect

A

Motor Effect rotates an object e.g. propeller, simple electronic motor, rotating CDs

26
Q

3 things magnetic field lines show on a bar magnet

A
  • The shape of the field
  • The direction (out of North pole, into South)
  • The strength of the field (lines closer together = stronger field)
27
Q

What does a split ring commutator do?

A

Ensures force on left of motor is always upwards and force on right is always downwards so that the coil turns continuously in one direction

28
Q

What device makes use that electricity can be created (induced) by a changing magnetic field?

A

Transformer

29
Q

What do transformers do?

A

Increase (step-up) or decrease (step-down) voltage

P3 (5 decks)

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