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Science 9 > Unit 4 - Topic 6 > Flashcards

Unit 4 - Topic 6 Flashcards

1
Q

Portable power uses

A

Batteries

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2
Q

Most electricity comes from conversion of

A

Mechanical energy

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3
Q

Mechanical energy associated w/

Examples

A

Any system w/ moving parts
Rotating windmill
Spinning turbines in thermo-electric, nuclear, geothermal power plants
Moving water of rivers/tides

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4
Q

Electric generator + surprising relationship

A

A device that converts mechanical energy into electric energy
Depends on relationship between electricity and magnetism

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5
Q

Hans Christian Oersted/1820 observations

A

Danish physicist
Relationship between electricity and magnetism
Compass needle turned when near wire carrying electric current
Amount of deflection depended on amount of current
When current reversed, needle moved in opp direction
When current interrupted, magnetic effects ceased

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6
Q

HCO fun fact

A

Wanted to show no relationship between electricity and magnetism
Proved himself wrong

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7
Q

Electromagnet

A

Strong temporary magnet, created by inserting a sift iron cure into a coil of wire and then passing a current through the wire

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8
Q

What happens in electromagnet when current passed through wire

A

One end of core becomes magnetic north pole and other the south pole

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9
Q

Variables to increase magnet strength

A

Wrap more coils around core
Increasing current passed through
Changing material of core

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10
Q

If direction of current is reversed …

If the current is turned off …

A

The polarity of the magnet is reversed

The iron core loses its magnetic properties

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11
Q

What’s stronger iron vs metals, woods, or plastics

A

Iron

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12
Q

Michael Faraday

A

Crediting w/ discovering basic principles of electromagnetism
Experiments formed basis of modern electromagnetic tech and electro chemistry
Introduced terms: ion, electrode, cathode, anode to science
Invented idea of lines of magnetic force

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13
Q

Unit for stored electric charge

A

Farad

Named after Faraday

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14
Q

Components of simple electromagnet

A

Electric power source
Wire
Soft iron bar

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15
Q

Individual atoms have

A

North and south pole

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16
Q

Magnetic domains in magnetized and unmagnetized

A

Atoms group together in which all north poles face same way
Or
Atoms have domains randomly arranged so magnetic effects cancel out

17
Q

Domains in magnet/electromagnet

A

Aligned

Resulting magnetic effects strengthened

18
Q

Why iron is effective core

A

Domains line up easily

Good in electromagnets

19
Q

Wire and magnet statement

A

Relative motion between a wire and magnet causes a current to flow in a circuit connected to the wire.
Voltage is “induced” when there is relative motion between the two
When wire connected to a circuit, “induced current” flows

20
Q

AC vs DC generator

A

Alternating current vs direct current

21
Q

Common AC generator

A

Coil of wire rotates inside stationary magnet
Coil rotated by external force
As wires in coil rotate, electrons begin to move in one direction
After one half revolution, current changes direction as electrons move other way
Current changes direction twice in one revolution hence name alternating current

22
Q

Hertz

A

Used to describe full waves each second for alternating current
Current changing direction 120 times per second would equal 60 Hertz or cycle AC

23
Q

Alternators

A

Generators that produce alternating current

24
Q

Why power plants produce AC

A

Relatively easy to increase or decrease voltage of

In order to travel long distances voltage must be increased then decreased for usage

25
Q

DC Generators

A

Also known as dynamo
Armature connected to outside circuit by split-ring commutator
As armature rotates in magnetic field current is produced
Brush touches metal split-ring which carries electrons to circuit
Insulating gap momentarily stops current however resumed once brushes touched again
Direction of charge flow in armature reversed but so has connection through commutator
As result current continues in constant direction

26
Q

Electric motor

A

Use electric energy to produce mechanical energy

27
Q

DC motor

A

Armature becomes electromagnet as current flows into it through split-ring comparator
Armature attracted and repelled by stationary field magnets so rotates
Commutator acts as switch cutting off then reversing direction of current flow to keep armature turning

28
Q

AC motor facts

A

Found in larger appliances

Have rotor and stator

29
Q

Rotor and stator defs

A

Rotating core

Stationary component surrounding rotor

30
Q

Rotor made up of

A

Non-magnetic conducting wires connected at ends and held in laminated steel cylinder

31
Q

Stator is what

A

Two-pole electromagnet

32
Q

AC motor workings

A

When turned on attraction and repulsion between magnetic poles of stator and rotor used to spin rotor

Science 9 (21 decks)

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