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Physics Paper 2 > Topic 7 > Flashcards

Topic 7 Flashcards

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1
Q

Magnetic field inside a solenoid

A

Strong and uniform

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2
Q

Magnetic field around a solenoid

A

Like that of a bar magnet

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3
Q

Increasing strength of magnetic field of solenoid

A

Add iron core

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4
Q

Electromagnet

A

Solenoid with an iron core

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5
Q

Loudspeakers

A

Convert variations in current to pressure using motor effect

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6
Q

Generator effect

A

When electric conductor moves relative to magnetic field or vice versa, potential difference produced across conductor

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7
Q

Induced current creates magnetic field that….

A

Opposes the original change (movement of conductor or change in magnetic field)

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8
Q

Generate ac

A

Alternator

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9
Q

Generates dc

A

Dynamo

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10
Q

What is in dynamo to make dc

A

Split ring commutators change direction of current every half turn

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11
Q

What alternators have to make ac

A

Brushes and slip rings so contacts don’t swap

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12
Q

Microphones

A

Use generator effect to convert pressure variations in sound waves into current variations

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13
Q

Why iron used in transformers

A

Easily magnetised

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14
Q

How solenoid increases magnetic effect of current

A

Field lines around each loop line up and lots in same direction
The closer the lines together the stronger the field

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15
Q

Things that affect size of force on conductor

A

Magnetic flux density (how many field lines in the region)
Size of current
Length of conductor in magnetic field

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16
Q

2 things that strength of magnetic field around wire depends on

A

Current

Distance from wire

17
Q

How loudspeakers work

A

Alternating current sent through wire attached to cone
Current uses motor effect causing force which moves cone
Alternating current causes opposite direction so cone moves in alternating direction
Creates variations of pressure in air causing sound waves
Frequency of sound wave same as of ac

18
Q

What an induced current always does

A

Creates magnetic field that acts against the change that made it eg movement of wire or change in magnetic field

19
Q

How to increase size of induced potential difference

A

Increase speed of movement

Increasing strength of magnetic field

20
Q

Transformers

A

Change size of potential difference of an alternating current

21
Q

Transformer: what induces alternating pd in secondary coil

A

Changing magnetic field as iron core magnetises and demagnetises

22
Q

Generator effect caused by either

A

Moving

Change in the magnetic field (transformers)

Physics Paper 2 (4 decks)

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