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Electrical D-1 > D-1 > Flashcards

D-1 Flashcards

1
Q

Definition of Compound

A

Contains atoms of more than one type

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2
Q

How many valence electrons would you find in
A) Conductor
B) Semi-conductor
C) Insulator

A

A) 1-3
B) 4
C) 5-8

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3
Q

Definition of the Fundamental laws of charged bodies?

A

Like charges repel, unlike charges attract

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4
Q

Two useful applications of electrostatic charge?

A
  1. Spray painting

2. Sandpaper manufacturing

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5
Q

Two hazards of electrostatic charge?

A
  1. Lightening

2. Fuel handling

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6
Q

6 methods that will create a difference of potential?

A
  1. Friction
  2. Chemical
  3. Pressure
  4. Heat
  5. Light
  6. Magnetism
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7
Q

How many electrons are equal to one coulomb?

A

6.23*10^18

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8
Q

Definition of voltage?

A

Potential difference

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9
Q

Definition of resistance?

A

Opposition to electron flow, measured in ohms

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10
Q

Define Ohms law?

A

The current flowing in an electric circuit that is directly proportional to the applied voltage and inversely proportional to the Resistance of the current

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11
Q

Define Watts law?

A

The power in a circuit equals the product of the voltage and the current in the circuit

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12
Q

Formulas for Ohms law?

A
  1. E=I*R
  2. I=E/R
  3. R=E/I
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13
Q

Formulas for Watts law?

A
  1. P=I*E
  2. I=P/E
  3. E=P/I
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14
Q

List the four main types of electrical drawings

A
  1. Pictorial
  2. Schematic
  3. Wiring
  4. Block/Line
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15
Q

What is the difference between a block diagram and a line diagram?

A

Block - Uses blocks

Line - Uses symbols

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16
Q

3 Characteristics of one-line diagrams

A
  1. Don’t show actual circuit position of components
  2. Labelled with name, type, catalog #
  3. No return path
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17
Q

What does a wiring diagram show?

A

Actual accurate infromation

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18
Q

On a wiring diagram when theirs a dot where two wires cross what does that mean?

A

That the wires are connected

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19
Q

What does a schematic diagram show?

A

The electrical relationship

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20
Q

Definition of circuit?

A

Circular journey or loop

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21
Q

What 3 condition’s MUST exist for a complete circuit?

A
  1. Source
  2. Load
  3. Conductor
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22
Q

Definition of short circuit

A

parallel path of low resistance

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23
Q

Definition of open circuit

A
  • Break in circuit
  • No current flow
  • Missing the source, load, or conductor
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24
Q

What is provided by a switch in a circuit?

A

A way to open/close a circuit

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25
Q

Why are circuit breakers and fuses added to circuits?

A

To protect components from having too much current flow through

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26
Q

Which way does current flow from the source out through the load?

A

negative to positive

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27
Q

List three handling and storage precautions for electrical meters?

A
  1. Shock and vibration
  2. Tempature, humidity, and dust
  3. Magnetic fields
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28
Q

What are the seven precautions you should consider when handling electrical measuring instruments?

A
  1. Never use a resistant measuring device on a live circuit
  2. Match meter to supply ex. DC-DC AC-AC
  3. Always observe the meter polarity when connecting into the circuit
  4. Check that the meter is orientated correctly to be read
  5. Look directly )Straight on) at pointer
  6. Select the range setting that gives the highest pointer deflection
  7. Switch it off
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29
Q

How should a voltmeter be connected when taking measurements in a circuit?

A

In parralel

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30
Q

How should ammeters be connected into a circuit for taking measurements?

A

In series

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31
Q

List five items that should be observed when using an ohmmeter?

A
  1. Never use on a live circuit
  2. Disconnect one end of the device to be measured from the circuit
  3. Everytime you change scales you must set it to zero again
  4. Always turn it off when done
  5. Do not touch both leads with your fingers
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32
Q

List the four things that should be observed when handling a wattmeter?

A
  1. Connect the voltage coil in parallel with the load
  2. Connect the current coil in series with the load
  3. Do not exceed the power rating of the meter
  4. You must observe the polarity of both coils
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33
Q

Definition of VOMS?

A

Volts, ohms, milliamps

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34
Q

What is a resistor?

A

Electrical component that introduces a specified amount of resistance into a circuit

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35
Q

How are resistors rated?

A

Ohms and watts

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36
Q

What are the three main classes of resistors?

A
  1. Wire wound - Higher wattage
  2. Film - Greater accuracy, lower wattage
  3. Carbon composition - small, cheap, very low wattage
37
Q

What is the main function of a switch?

A

Control the flow of current

38
Q

What is the main function of fuses and circuit breakers?

A

Break circuit before damage is done

39
Q

What should switches be marked with?

A

Rated voltage and current

40
Q

List four different types of switches?

A
  1. Dimmer switch
  2. 3 way switch
  3. 4 way switch
  4. Single pole switch
41
Q

List the three basic types of fuses?

A
  1. Cartridge fuses
  2. Plug fuses
  3. Renewable link fuses
42
Q

What is the most common type of circuit breaker?

A

Moulded case breaker

43
Q

What is the function of a trip element in a circuit breaker?

A

Trigger the operating mechanisms in the event of a prolonged overload or excessive current magnitude and cause the circuit breaker to open

44
Q

What are the two basic types of trip elements?

A
  1. Thermal trip element

2. Magnetic trip element

45
Q

Definition of oxidation?

A

Result of oxidizing or being oxidized

46
Q

Definition of Ductility

A

Ability of a material to be drawn into a wire

47
Q

Definition of malleability

A

Ability of a material to be rolled or hammered into thin sheets

48
Q

Why s copper the most commonly used conductor?

A
  • Easy to work wit
  • Does not oxidize much
  • Solders readily
49
Q

What are three major problems of using aluminum as a conductor?

A
  1. Oxidize forms easily
  2. Aluminum reacts with some other metals
  3. Cold flow
50
Q

What are the three shapes a bus bar can come in?

A
  1. Solid square
  2. Solid rectangle
  3. Hollow tube
51
Q

What are the purposes of the conductor insulation?

A

To prevent unwanted flow of electrical current, such as ground faults, short circuits or electric shock.

52
Q

List five types of insulating materials used for conductors?

A
  1. Enamel
  2. Varnished cambric
  3. Rubber
  4. Thermoplastic
  5. Minerals
53
Q

Definition of power circuit wiring?

A

means conductor and cable installation for the distribution of electrical energy within residential, commercial, and industrial buildings

54
Q

What s the difference between the service equipment and the branch circuits?

A

Service equipment- Main power source for all other circuit wiring

branch circuits- Supply lightening, receptacle, heaters, dryers, motors

55
Q

What does the code define as low voltage?

A

31v -750v

56
Q

What does the code define as extra low voltage?

A

30v or less

57
Q

List three ways in which a body may receive an electrostatic charge?

A
  1. Friction
  2. Conduction
  3. Induction
58
Q

Formula for line drop

A

E=i*r

59
Q

Formula for line loss ?

A

P=i^2*r

60
Q

Formula for voltage drop ?

A

Eload=esupply-edrop

61
Q

Definition of matter ?

A

Anything that occupies space or has mass. It can exist in any of 3 states. Liquid, solid, gas

62
Q

What is the difference between an atom and a molecule ?

A
  1. A molecule can be an an independent unit of compound or an element, but an atom can only be the smallest unit of an element
  2. A molecule must be independent but the atom does not have to be
63
Q

List three ways in which a body may receive an electrostatic charge ?

A
  1. Friction
  2. Conduction
  3. Induction
64
Q

Definition of field force ?

A

A force that acts at a distance without physical contact

65
Q

Definition of polarity ?

A

Refers to the charge at one point with respect to another

66
Q

List 6 methods of producing energy ?

A
  1. Friction - triboelrctic effect
  2. Chemical - electrochemical effect
  3. Pressure - piezoelectric effect
  4. Heat - thermocouple
  5. Light - photovoltaic cell
  6. Magnetism - electromagnetic effect
67
Q

State the law of conservation of energy ?

A

Energy can neither be created or destroyed

68
Q

Formula for voltage ?

A

Joules/ coulomb

69
Q

Formula for Amps

A

A=coulomb/second

70
Q

Formula for efficiency ?

A

Efficiency= output watts/input * 100

71
Q

Formula for horsepower ?

A

Hp=out/746

72
Q

Definition of load ?

A

A device that changes electrical energy into other forms of energy

73
Q

What will happen if you connect a DC meter to the wrong polarity ?

A

May be damaged as the pointer tries to deflect the wrong way

74
Q

Definition of parallax Error?

A

The type of reading error that takes place when you do not look at the needle straight on

75
Q

What are the three ratings you must be careful not to exceed when you are using a wattameter ?

A
  1. Voltage coil
  2. Current coil
  3. Power
76
Q

Voltmeters ?

A

Used to measure a difference of potential between two points

77
Q

Ammeters ?

A

Designed with as low a resistance as possible so that they do not add unwanted resistance to the circuit

78
Q

Wattmeter ?

A

Has four test leads. Two are for measuring current, and two for voltage

79
Q

Ohmmeter?

A

Used to measure resistance

80
Q

Colour code

A 
Black -black
Boys - brown
Rape - red
Our - orange
Young - yellow
Girls - green 
But - blue 
Violet- violet 
Goes- grey 
Willings - white 
Sometimes for gold
Sometimes for silver
Sometimes for nothing at all
81
Q

What three purposes are resistors used ?

A
  1. Limit current
  2. Provide a change in voltage
  3. Produce heat
82
Q

In what unit is resistor rated ?

A

Ohms and watts

83
Q

Identify 3 types of fixed resistors ?

A
  1. Wire round resistor
  2. Film resistor
  3. Carbon- composition
84
Q

Which resistor has the lowest watts rating ?

A

Carbon-composition resistors

85
Q

What Ratings should switches have marked on them ?

A

Rated voltage and current

86
Q

Snap switches ?

A

Used to control incandescent and fluorescent lamps

87
Q

What shortcoming did the original Edison’s fuse have ?

A

Could easily be replaced with one of higher amp rating

88
Q

Definition of conductor ?

A

A material that allows electrical current to flor with relative ease

89
Q

4 factors effecting resistance ?

A
  1. Natural resistance
  2. Length
  3. Area
  4. Temp

Electrical D-1 (1 decks)

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