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L Theory > L Theory > Flashcards

L Theory Flashcards

Learn about L theory you dip shit

1
Q

What holds electrons in orbit around the nucleus?

A

A force of attraction

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2
Q

What is the outer orbit of the atom called?

A

Valence shell

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3
Q

What is outer electron in the atom called?

A

Valence electron

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4
Q

What is the polarity of an electron?

A

Negative

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5
Q

If an electronic is removed from an atom, what is it called?

A

Free electron

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6
Q

If an electronic is removed from an atom, what is the atom called?

A

Positive ion

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7
Q

Electrons flow from…?

A

Negative to positive

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8
Q

What is conventional flow?

A

Positive to negative

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9
Q

What is the circuit (equation) symbol for current?

A

I

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10
Q

What is current measured in?

A

Amps

Amperes

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11
Q

A material with lots of free electrons to allow current us called a….?

A

Conductor

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12
Q

Give 4 examples of a conductor?

A

Copper
Gold
Brass
Steel

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13
Q

A material with very few free electrons that doesn’t allow current through us called a…?

A

Insulator

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14
Q

Give 4 examples of an insulator?

A

Rubber
Plastic
Wood
Paper

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15
Q

What are the 4 factors that will effect the resistance of a conductor?

A

Length
Cross sectional area
Temperature
Type of material used

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16
Q

How will increasing the length of a conductor effect the resistance?

A

Increase the resistance

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17
Q

How would increasing the temperature change the resistance?

A

Increase of resistance

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18
Q

How does increasing the cross sectional area effect the resistance of a conductor?

A

Decreases the resistance

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19
Q

State ohms law in full

A

The current in a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance provided the temperature remains constant

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20
Q

What is the unit of resistance?

A

Ohms

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21
Q

State the formula for calculating resistance in a series circuit

A

Rt = R1 + R2 + ….

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22
Q

State the formula for calculating the resistance in a parallel circuit

A

1/Rt = 1/R1 + 1/R2 + ….

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23
Q

After working out the total resistance in a parallel circuit, what is a good check to see if you’re correct?

A

The total resistance is lower than the smallest resistor

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24
Q

What is the name of a naturally magnetic ore?

A

Magnetite

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25
Q

There are lines of force that surround a magnet, what are these called?

A

Lines of magnetic flux

26
Q

What direction do the lines of magnetic flux travel?

A

North to South

27
Q

What are 2 types of commonly used permanent magnet?

A

Bar

Horseshoe

28
Q

What will happen if 2 like poles are brought together?

A

They will repel

29
Q

What will happen if 2 unlike poles are brought together?

A

They will attract, stick together and magic stuff

30
Q

What are 3 materials that, when added to steel, make the magnet stronger?

A

Nickel
Cobalt
Aluminium

31
Q

What is produced around a conductor when a current is passed through it?

A

A magnetic field

32
Q

Name 3 methods of producing a magnet?

A

Permanent magnet
Electro magnet
Rubbing a permanent against a none magnetic iron bar

33
Q

What are the 3 requirements to induce a voltage by induction?

A

A conductor
Relative motion
Magnetic field

34
Q

Will a transformer work with DC?

Why?

A

No

Because it requires an alternating magnetic field created by AC flow

35
Q

List 2 types of transformer construction

A

Shell

Core

36
Q

What is the main purpose of a transformer?

A

To change the voltage of an AC line

37
Q

What us the purpose of the laminated iron core?

A

To reduce edicurrents which increases the efficiency

38
Q

If there are more coils on the secondary coil than in the primary, what type of transformer is it?

A

Step up

39
Q

State the output voltage equation?

A

(Number of primary coils/number of secondary coils) = (primary voltage/secondary voltage)

40
Q

What is the purpose of a centre tapped transformer?

A

Reduces the harm done by touching a live wire as it will halve the voltage across your body

41
Q

Identify the the cables used on a HM ship

A

Red - phase 1, L1
Yellow - phase 2, L2
Blue - phase 3, L3

42
Q

State the new colour codes for phases

A

Brown - phase 1, L1
Black - phase 2, L2
Grey - phase 3, L3

43
Q

What are the advantages of an AC motor?

A

Small
Light
Less maintenance
More efficient

44
Q

What is the main disadvantage to an AC motor?

A

Difficult to vary speed output

45
Q

What are the 2 main components to an AC motor?

A

Stator

Rotor

46
Q

What causes motion in an induction motor?

A

The stator creates a rotating magnetic field
The rotating magnetic field creates a current in the copper bars of the rotor
The rotor generates a magnetic field which tries to follow the rotating magnetic field

47
Q

What is the most common types of AC motor on HM ships?

A

Squirrel cage motor

48
Q

List the components of a squirrel cage motor

A 
Rotor
Stator
Free and shaft end bearings
Free and shaft end copper rings
Copper bars
49
Q

Why is there less maintenance on an AC motor?

A

No carbon brushes or commutator

50
Q

What would happen is a 3 phase motor was to lose a phase?

A 
Vibrates
Lots of noise
Low power
Will continue running
Will heat up
51
Q

If a shut down 3 phase motor was to lose 1 phase, what would happen if you tried to start it?

A

It wouldn’t start

52
Q

A potential difference will exist between 2 points that have a…?

A

Difference in charge

53
Q

What is potential difference measured in?

A

Volts

54
Q

What is the name of the force that drives a current through the circuit?

A

Electromotive force

55
Q

Name 6 methods of how voltage can be created

A 
Light
Induction
Heat 
Friction
Pressure
Chemical
56
Q

To produce a chemical voltage, the 2 plates must be made of…?

A

Different metals

57
Q

Give an example of where friction creates voltage

A

Rubbing a woolen cloth on a glass rod and then dumping the electrons on a carbon rod

58
Q

What determines the polarity of an induced voltage?

A

The direction of polarity of the moving magnetic field

59
Q

What determines the voltage produced by a thermocouple?

A

The types of metal used

Heat difference

60
Q

What is a solar panel made of?

A

Semi conductor

L Theory (1 decks)

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