6 MAGNETISM + ELECTROMAGNETISM Flashcards

1
Q

What do magnetics do to magnetic substances

A

Attract them

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2
Q

Attraction of like poles

A

Repel

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3
Q

Attraction of unlike poles

A

Attract

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4
Q

Where do magnetic field lines run

A

North to South

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5
Q

Define a magentic field line

A

The direction of force on a small NorthPole at that point

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6
Q

What is a magnetically soft material

A

A material that gains and looses magnetism easily

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7
Q

How to draw uniform magnetic field lines

A
  • Straight and with arrows from N -> S
  • Close together = stronger force
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8
Q

What is a neutral point of a N-N magnet

A
  • In the centre between field lines, where there is no magnetic field
  • Magnetic forces balance (cancel)
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9
Q

How to investigate magnetism with iron filings

A
  • Place magnet on desk, then paper over, and around with pencil marking north pole
  • Carefully sprinkle iron filings on top
  • Tap the paper to allow them to fall into place
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10
Q

How to investigate magnetism with plotting compasss

A
  • Place magnet on piece of paper and draw around in pencil and mark north pole
  • Place plotting paper on compasss
  • Draw around plotting compass, and mark direction of arround with ‘x’
  • Move plotting compass, so tail of arrow is on ‘x’ and mark direction again
  • Repeat to build up field pattern
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11
Q

Unit for current

A

Ampere (A)

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12
Q

Unit for power

A

Watt (W)

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13
Q

Unit for voltage

A

Volt (V)

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14
Q

What happens when an electrical current flows through a conductor

A

It produces a magentic field around it

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15
Q

How do you increase the strength of an electromagnet

A
  • Add a soft iron core
  • Increase the current
  • Add more coils
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16
Q

What rule is used to observe the magentic field in a straight wire

A

Right thumb grip

17
Q

Why does the middle area of a flat coil have a strong magnetic field

A

As the fields add

18
Q

What is the magnetic field of a solenoid

A

Same as bar magent
* North = current in
* South = current out

19
Q

What does a CROSS represent on an electromagnetic drawing

A

Current moving AWAY

20
Q

What does a DOT represent on an electromagnetic drawing

A

Current moving TOWARDS you

21
Q

Describe how the motor effect works

A
  • Magnetic field of bar magnet interacts with the magnetic field created by current in the wire
  • Strong field one side where 2 forces add, and weaker where 2 forces subtract
  • Wire moves up/down due to motor effect
22
Q

What must the components of flemming’s left hand rule be at

A

90’

23
Q

What must the components of flemmings right hand rule be at

A

90’

24
Q

First finger in flemming’s rules

A

Magnetic Field (North to south)

25
Q

Second finger in flemming’s rules

A

Current ( + to - )

26
Q

Thumb in flemming’s rules

A

Motion

27
Q

How can you make an object move faster that’s undergoing the motor effect

A

Increase current or Stronger magnets

28
Q

How is current induced

A

When a wire cuts through a magnetic field

29
Q

How do you increase current in electromagnetic induction

A
  • Stronger magnets
  • Faster Movement
  • More coils
  • Larger Coils
30
Q

How does a transformer work

A
  • Pass AC current through primary coil
  • Primary coil becomes an electromagnet, creating a changing magnetic field
  • Changing field in channelled into secondary coil by soft iron core
  • Changing field induces a voltage into secondary coil
31
Q

Why is electricity transported at a low current, and high voltage

A

To reduce power loss

32
Q

Use of step-up transformer

A

Increase voltage to decrease power loss

33
Q

Use of step-down transformer

A

Decrease voltage so appliances aren’t damaged

34
Q

Transformer equation

A

Primary Voltage / Secondary Voltage = Primary Turns / Secondary Turns