P15 (Magnetism) Flashcards

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1
Q

Properties of magnets

A
  • two poles, north and south
  • produce magnetic field
  • non contact force
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2
Q

2 Types of forces in a magnet

A
  • attraction

- repulsion

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3
Q

How does a compass work?

A
  • tiny bar magnet
  • north pole attracted to south pole of any other near magnet
  • points in the direction the magnetic field is in
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4
Q

Permanent magnet

A
  • produce their own magnetic field
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5
Q

Induced Magnet

A
  • magnetic material that turns into a magnet inside a magnetic field
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6
Q

The right- hand rule

A
  • do the ‘thumbs up’

- when a current flows through a wire a magnetic field is created around the wire

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7
Q

What determines the strength of a magnetic field

A
  • larger current

- closer to the wire

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8
Q

Solenoid + increase strength

A
  • coil of wire

- increase strength by wrapping more wires into a coil

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9
Q

What is an electromagnet?

A
  • solenoid with an iron core (where magnetic field can be turned on and off through a current)
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10
Q

2 Uses of Electromagnets

A
  • used for scrap yards pick up metals

- used within other circuits to act as switches

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11
Q

Motor effect

A
  • current carrying wire is put between magnetic poles
    – the magnetic field around the wire interacts with the magnetic field it has been placed in
    – magnet on the conductor exert a force on each other so the wire moves
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12
Q

Describe the interaction between the magnetic field and the direction of current (motor effect)

A

The force acts at right angles to the magnetic field of the magnets and the direction of the current

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13
Q

Fleming’s left-hand rule

A

– First finger is the direction of the field
– second finger (to the rights) direction of the currents
- thumb is the motion (force)

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14
Q

How loud speakers work

A

– And AC current is sent for a coil of the wire
– the coil surrounds one poll of a permanent magnet and is surrounded by another pole so a current causes of force on a coil (cone moves)
- variation in current makes the cone vibrate
- pressure causes sound waves

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15
Q

The generator effect

A

– The induction of a potential difference in a wire is moving relative to a magnetic field, or experiencing a change in magnetic field

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16
Q

Alternators

A

– Generate alternating-current
– rotate a coil in a magnetic field
- as the coil spins a current is induced in the coil, the current changes direction every half turn

17
Q

Dynamos

A

This swap is the connection every half turn to keep the current flowing in the same direction

18
Q

Transformers

A

– They change the size of the potential difference of an alternating-current
– two coils (primary and secondary) joined with an iron core

19
Q

Step up transformers

A

– Step the potential difference up, they have more turns on the secondary coil

20
Q

Get down Transformers

A

Step the potential difference down, they have more turns on the primary coil