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Electrical Theory Basics > Ch 1 > Flashcards

Ch 1 Flashcards

1
Q

The Law of Attraction and Repulsion of magnets states:

A

Like poles repel each other and unlike poles attract each other

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2
Q

This is the result of the atomic bonding of two or more atoms

A

Compounds

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3
Q

What would you use to protect the electrical equipment in a building?

A

Surge protectors

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4
Q

What will a magnet align itself with if it is hung freely from a piece of string?

A

Earth’s magnetic field

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5
Q

What keeps electrons from breaking out of their orbit around the nucleus?

A

Law of electrical charges

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6
Q

When a magnet is hung freely, what do you call the end that is pointing north?

A

north-seeking pole

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7
Q

What do you call a switch that uses an electromagnetic field to open or close a set of contacts?

A

Electromagnetic Relay

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8
Q

When atoms of elements combine they produce _____

A

Compounds

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9
Q

Some crystalline materials produce a small electrical voltage when bending or twisting pressure is applied to them, what is the effect?

A

Pressure (Piezoelectricity)

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10
Q

Illumination is produced when a source of energy strikes phosphorus materials

A

Phosphorescent illumination

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11
Q

The conductor that rotates between the stationary magnetic field poles of the stator is called what?

A

Rotor or armature

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12
Q

What is the maximum let-go threshold for women and men?

A

10mA and 16 mA

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13
Q

What is the only naturally occurring magnet?

A

Lodestone

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14
Q

When energy is applied to valence electrons, it is divided evenly among them, how does that affect them?

A

Fewer valence electrons for a given amount of energy means each valence electron receives more available energy.

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15
Q

What causes the armature of a dc motor to rotate?

A

The repelling forces of similar magnetic polarities and the attracting force of opposing polarities.

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16
Q

How many shells are around the nucleus of an atom where electrons orbit?

A

7

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17
Q

This is the process where heat is applied to dissimilar metals that are joined together to produce about 5 to 30 thousandths of a volt.

A

Thermoelectric effect

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18
Q

(T/F) A magnet will affect a compass?

A

True

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19
Q

What forces the rotor to rotate in a generator?

A

Prime Mover

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20
Q

What materials make up permanent and temporary magnets?

A

Hard Steel & Soft Iron

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21
Q

What do you call the stationary magnetic field around a dc motor?

A

Stator

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22
Q

Compounds can change the _____ _______ of the individual atoms

A

electrical characteristics

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23
Q

What does a clamp-on AC ammeter detect?

A

The rising and falling and falling of the magnetic field around the conductor.

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24
Q

What dictates the distance an arc can jump?

A

Voltage & Dielectric

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25
Q

(T/F) Lightning strikes both metallic and nonmetallic objects with the same frequency?

A

True

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26
Q

(T/F) Both AC and DC electromagnetic fields are used to operate motors and relays

A

True

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27
Q

(T/F) Ions can be positively or negatively charged?

A

True

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28
Q

The smallest particle of a compound is called what?

A

Molecule

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29
Q

(T/F) You cannot have normally open and normally closed contacts in a single relay?

A

False

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30
Q

What is lightening protection intended to protect?

A

The building itself, not the electrical equipment.

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31
Q

What happens when you demagnetize a magnet?

A

The molecules are disarranged to their original orientations

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32
Q

What is the condition in which an atoms valence shell is completely filled?

A

Chemical Stability

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33
Q

Which direction do the lines of force on electrons and protons go?

A

Electrons - In : Protons - Out

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34
Q

This has a moving coil, a dc battery supply, and is connected in series with he resistor being measured.

A

Ohmmeter

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35
Q

Illumination is produces when a high-resistance tungsten metal filament is heated in a vacuum glass lamp

A

Incandescent

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36
Q

The closer the flux lines and the greater number of flux lines means what?

A

The stronger the magnetic field

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37
Q

What device would you use to measure very high resistance and what is the voltage range it would be used in?

A

Megohmmeter, (500-1000V)

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38
Q

Once enough energy has been applied to force an electron out of it orbit, where will it go?

A

Towards a positive charge or away from a negative charge

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39
Q

Why is copper a better conductor than aluminum?

A

It has less valence electrons

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40
Q

The complete path electrons take is called ______

A

electrical circuit

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41
Q

How many valence electrons do insulator atoms have?

A

6-8

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42
Q

What is the outermost shell of an atom called?

A

Valence

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43
Q

In DC ammeters, actual circuit current is connected in _______ with the meter coil?

A

Series

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44
Q

How does a voltmeter work? (analog)

A

There is a coil around a soft iron bar and when current flows through the coil it creates an electromagnetic field which exerts force on the iron bar and moves it.

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45
Q

What is it called when there is an excess of, or a deficiency of, electrons between objects that have been separated?

A

Static Charge

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46
Q

What do you call the movement of electrons for the purpose of transferring energy to perform useful functions?

A

Electricity

47
Q

(T/F) Flux lines travel North to South and can cross

A

False

48
Q

What is a voltmeter is used to measure?

A

AC / DC voltage

49
Q

When you magnetize and iron bar, what happens that makes it become magnetic?

A

The molecules align in the same direction

50
Q

If you are measuring a current larger than 10 mA, with a directly connected meter what is often required? How is it installed?

A

A resistor, called a “shunt” ; In parallel with the meter movements coil.

51
Q

How and where is most of the electrical energy utilized today created?

A

Power plants, they rotate a magnetic field through a conductor

52
Q

What happens to electrons when two conductive materials separate?

A

They go back to their original surface before the separation is complete

53
Q

The movement of electrons from their atoms is the basis of_____

A

Current flow (electricity)

54
Q

Everything on earth that occupies space and has weight is called what?

A

Matter

55
Q

(T/F) A bar of soft iron makes a stronger magnet than hard steel?

A

True

56
Q

Air terminals are often called what?

A

Lightening rods

57
Q

What is the law of electrical charges?

A

Particles with like charges repel each other and particles with unlike charges attract

58
Q

A DC generator requires the magnetic field of the stationary field (stator) to be produced from a _______ or ____ that is always in the same direction.

A

permanent magnetic : electromagnetic field

59
Q

Are semiconductor atoms better used for insulating or conducting?

A

They can be used for both

60
Q

This is a term that refers to the relative ease at which material can be magnetized

A

Permeability

61
Q

This process builds up layers of metal on one surface and removes the same metal from another by the chemical action of an electric current in a solution

A

Electroplating

62
Q

Conductive materials are made up of materials that have how many valence electrons?

A

1-3

63
Q

The magnetic field of a magnet is visualized as what?

A

Flux lines

64
Q

The attracting and repelling force of subatomic particles is sometimes referred to as what?

A

Electrostatic Field

65
Q

(T/F) DC current is used to produce an alternating electromagnetic field that is necessary for the operation of transformers

A

False

66
Q

Materials that are good conductors of magnetic force are called _____

A

Magnetic Materials

67
Q

Power source consisting of voltaic cells combined in a series arrangement

A

Battery

68
Q

What is the maximum number of electrons allowed in valence shell?

A

8

69
Q

If a magnet loses its magnetism quickly, what is it called?

A

Temporary magnet

70
Q

What dictates the temperature of an arc?

A

Amperage

71
Q

______ Means that the contacts are closed when the relay is not energized, but open when the relay is energized

A

Normally Closed

72
Q

______ Means that the contacts are open when power is not applied to the coil, but the contacts close when power is applied

A

Normally Open

73
Q

What do you call charged atoms?

A

Ions

74
Q

Photoelectricity works on the principle that ____

A

light (photons) striking a semiconducting plate causes it to release electrons to another semiconducting plate

75
Q

An electric fault can cause a severe arc blast with temperature up to how high?

A

30,000 degree F

76
Q

How many shells are around an atom?

A

7

77
Q

Which electrons are more susceptible to being separated from their atomic structure and why?

A

The electrons furthest away because their attraction becomes weaker the farther away their orbit is from the nucleus.

78
Q

Light is produced when an electric arc flows through a charged gas lamp

A

Electric Discharge Lighting

79
Q

Illumination results from the combination of electroluminescence and phosphorescence when electric current flows through a charged gas or vapor causing the emission of invisible, ultraviolet radiation, which strikes a phosphorescent coating.

A

Fluorescent lighting

80
Q

What would you do to prevent corrosion on low voltage electronic circuitry conductors?

A

Apply gold or silver plating to the copper cable terminals

81
Q

In order for current to flow from the power source through the appliance / equipment and back to the power source the current flow path must be _______

A

conductive

82
Q

Semiconductor atoms contain how many valence electrons?

A

4-5

83
Q

Electric current can produce light in these four different ways:

A

Incandescent, Electric Discharge, Phosphorescent, and Fluorescent

84
Q

What are the principles in which electric motors work?

A

Attracting and repelling forces of a magnetic field

85
Q

How does an atom become chemically stable?

A

Atomic bonding

86
Q

What subatomic particle is the lightest?

A

Electrons

87
Q

This converts gaseous fuel, such as natural gas or propane, into electrical energy

A

Fuel Cells

88
Q

Steel and ____ metals have magnetic properties (excepts stainless steel)

A

ferrous

89
Q

What do you use to protect buildings and structures from lightening discharges?

A

Air terminals (lightening rods)

90
Q

What are 5 ways to force electrons to move?

A

Heat, Pressure, Light, Magnetism, and Chemical Activity

91
Q

DC voltmeters are connected in ______ with the circuit and measure the _________ of potential between the two test leads.

A

Parallel : Difference

92
Q

In a holding relay, what makes it safe?

A

One the relay is de-energized, the power to the equipment will be removed and the only way to re-energize the circuit is to push the start button.

93
Q

An electric shock from as little as ____ volts ac for as little as ______ can disrupt the heart’s electrical circuitry causing it to go into ventricular fibrillation

A

30V , One second

94
Q

What is the generally accepted theory about what magnets are made of?

A

They are made up of a very large number of small magnets. If molecules in an iron-based metal are pointing in the same direction, the magnetic fields add together.

95
Q

What happens if you connect a dc ammeter in parallel with the load?

A

The meter will operate at the source voltage and the current flowing through it will be extremely high. It will most likely destroy the meter if it doesn’t have internal protection.

96
Q

How does magnetism (magneto electricity) work?

A

It isn’t the force of the magnetic field moving through a conductor that produces electricity, it is the relative motion of the magnetic field to the electrons within the conductor. The magnetic field pulls or pushes electrons through the circuit.

97
Q

What do you call the attractive force between a proton and electron?

A

Electrostatic field

98
Q

What do you call a high-current discharge that temporarily neutralizes the positive and negative charges between objects?

A

Stroke

99
Q

Are high-voltage cells in lightning usually positively or negatively charged?

A

Negatively

100
Q

What are two ways to magnetize an iron bar?

A

Electric current or magnetic stroking

101
Q

Term that refers to how much magnetic materials can retain magnetism?

A

Retentativity

102
Q

This is used for extremely accurate resistance measurements

A

The Wheatstone Bridge

103
Q

How does an electric motor work?

A

A conductor that has current flowing through it creates an electromagnetic field around the conductor and is placed inside a stationary magnetic field of a dc motor which causes the free moving conductor to move

104
Q

What is the principle behind appliances such as toasters and ovens?

A

Heat (resistance) electricity is sent through a high resistance heating element that produces heat as electrons flow through the circuit.

105
Q

What are the three methods used to demagnetize a magnet?

A

Hard blow, heat, or ac field

106
Q

What do you call the discharge of high voltage cells within clouds to each other, the earth, and sometimes space?

A

Lightning

107
Q

In a voltmeter, what would cause the iron bar to go farther into the coil?

A

The greater the voltage, the greater to current flow through the meter, the greater the magnetic field is produced which pulls the iron bar is drawn in.

108
Q

What does an ohmmeter measure?

A

Resistance or opposition to the current flow of a circuit or component.

109
Q

Ionized paths that zigzag toward earth

A

Stepped Leaders

110
Q

On an AC generator, which of these is stationary and which of these is revolving: Magnetic Field & AC Winding.

A

Magnetic field is revolving and the AC Windings are stationary.

111
Q

How does a generator operate?

A

Prime Mover forces the armature to rotate while it is subjected to the static magnetic field of the stator which forces electrons in the conductor to move

112
Q

How high of voltage & current can a lightening bolt have?

A

30 million volts / 20 thousand amps

113
Q

Using electric current to alter the effects of chemical bonding so as to separate or encourage the formation of new compounds is the basis of ______ & ______

A

Electroplating and Electrolysis

114
Q

An atom contains how many subatomic particles and what are they?

A

3, Electrons : Protons : Neutrons

Electrical Theory Basics (11 decks)

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