Electromagnetic Forces & Induction Flashcards

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1
Q

How to find the direction of field lines?

A

Right hand rule
Thumb = Direction of current
Fingers = Direction of field

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2
Q

Field lines/ Current goes from?

A

North(out) to South(in)
Positive(out) to Negative(in)

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3
Q

How do you reverse magnetic field?

A

Reverse direction of current flow ( flip the battery)

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4
Q

Ways to increase strength of a magnetic field?

A
  1. Increase current
  2. Increase turns of coil
  3. Add an iron core
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5
Q

Flemings left hand rule

A

Pointer is field
Middle is Current
Thumb is Motion

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6
Q

When will a wire give full force?

A

When the wire is at 90 degrees to the magnetic field

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7
Q

What is an emf?

A

Electromotive force

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8
Q

What is electromagnetic induction?

A

Process of generating electricity from motion

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9
Q

How to increase electromotive force in a coil/wire

A

1 use stronger magnet
2 move the coil quickly relative to the magnet
3 use a coil with more turns of wire

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10
Q

Factors that affect size and direction of emf

A

1 No cutting of field lines when magnet is still
2 Wire and magnet are far, fewer field lines cut
3 Magnet moved quickly, More field lines cut => bigger emf
4 Coil effect > wire effect

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11
Q

A.C AND D.C generator?

A

Alternating current (2 rings)
Direct current ( 1 split ring)

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12
Q

Increase voltage in an A.C generator?
(increase rate at which field lines are cut)

A

1 Turn coil faster
2 Use a coil with more turns of wire
3 Use coil with bigger area
4 Use stronger magnets

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13
Q

Lenz’s law?

A

Direction of induced current always opposes change in circuit

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14
Q

Why use high voltages

A

High voltage = low temp
Low voltage = high temp => fires etc

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15
Q

What are transformers?

A

Changes voltage of an a.c supply

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16
Q

Step up and step down?

A

SU- Increases voltage
SD- decreases voltage

17
Q

Formula for power loss?

A

P= I squared x R

18
Q

Parts of transformer?

A

Primary coil, Secondary coil and iron core

19
Q

Formula: Power in and power out?

A

Primary I x Primary V = Secondary I x Secondary V

20
Q

Type current that generator and electromagnet use

A

AC current