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General Maintenance (physics, math, and electrical) > Electricity > Flashcards

Electricity Flashcards

1
Q

Formula for Volts, Amps, and Resistance

A

Amps * Ohms

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2
Q

What is a side effect of energy loss in resistance

A

Temperature increase

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3
Q

What is the purpose of resistors

A

to limit current flow

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4
Q

What is ohms/amps/volts Series circuit rules

A

Total Resistance is summed
Amps is equal throughout the circuit
Voltage is summed

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5
Q

What effect is created when you put electricity through a conductor and what can increase the effect

A

A Magnetic Field

Spiraling the wire causes the magnetic field to amplify and putting soft iron core in the spiraling wire increases the magnetic field

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6
Q

What is Rheostat Resistor

A

Changeable resistance resistor

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7
Q

What is a Potentiometer Resistor

A

Changeable resistance resistor

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8
Q

What is a Tapped resistor

A

Resistor separator

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9
Q

What is a Thermo-resistor

A

Changeable resistor by temperature

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10
Q

What is a Photo-resistor

A

Changeable resistor by light

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11
Q

Tolerance defined

A

The range of a product that can be higher or lower (+ or -)

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12
Q

Ohms/Amps/Volts Parallel Circuit Rules

A

Amps are not constant
Voltage is constant
Total Resistance is lower then the lowest resistance

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13
Q

Formula for Parallel Resistance

A

1/((1/R1)+(1/R2)+(1/…))

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14
Q

What is a battery rating

A

Sum of the batteries voltage

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15
Q

one HP equals how many watts

A

746 watts

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16
Q

Watts Formula

A

Watts = Amps * Volts

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17
Q

What is Amps, Voltage, Watts, and Ohms purpose

A 
Amps = Strength of the circuit 
Voltage = the motion of the circuit 
Watts = Power of the Circuit
Ohms = Resistance of the circuit
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18
Q

What is polarity and what is the flow of a circuit

A

Polarity is direction of the circuit

Electrons flow from Negative pole (High Density of Electrons) to Positive Pole (Low Density of Electrons)

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19
Q

How do Amp, Ohms, and Volt meters added to a circuit

A

Ammeter is series

Voltmeter is parallel

Ohmmeter is isolated series

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20
Q

What is a Short Circuit and what are the effects

A

Unintentional path to ground

Effects are burning due to over-voltage or open circuit

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21
Q

Open Circuit Defined

A

Incomplete circuit

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22
Q

What is the Electrical Troubleshooting Checklist

A

Confirm the fault

  • Check for Shorts with Volt/Ohm/Amp meters
  • Check for Opens with Voltmeter
  • Check Specific Components with Ohmmeter
  • Check for correct wiring with Ammeter

Fix The fault

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23
Q

What are the characteristics of AC

A

Efficient in longer ranges, smaller wiring required due to less resistance, Circuit breakers are less likely to arc at higher altitudes

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24
Q

AC Defined

A

electricity that constantly changes direction and intensity

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25
Q

When can magnets induce electricity on a conductor

A

Only when the conductor is perpendicular to the lines of flux

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26
Q

What does a magnetic field induce on a conductor

A

Only voltage constantly and a current only is created when the conductor is being induced or removed from induction

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27
Q

Define Cycle and Frequency

A

Cycle is repetition of the sine wave pattern

Frequency is cycles per second

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28
Q

Define Phase Relationships, In-Phase, or Out-Phase

A

Phase Relationships are timing and degrees of two currents

In-Phase is when Voltage/Amps are on same degree and time

Out-Phase is when Voltage/Amps are off degree and time

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29
Q

Instantaneous Value Defined

A

The amp value or voltage value at a certain degree and time

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30
Q

Define Capacitors

A

Short term energy storage unit, that releases charge when pressure is released in the circuit

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31
Q

What prevents arcing in a capacitor

A

Dielectric

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32
Q

Why do capacitors stop current

A

Capacitive Reactance, The walls get filled with too many electrons on both walls preventing flow of electrons in the wire due to repulsion of liked charges

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33
Q

What are the three factors that create resistance in a AC circuit

A

Resistors, Inductive Reactance, Capacitive Reactance

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34
Q

What increases the amount of electrons a Capacitor can hold

A

Plate area, Spacing of Dielectric, Dielectric Material

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35
Q

What causes the capacitor limit to be exceeded

A

If Voltage is to high he dielectric breaks down and arcing occurs

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36
Q

What is the formula for capacitance in series and Parallel

A

Series: 1/((1/C1)+(1/C2)+(1/…))

Parallel: Sum

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37
Q

What is capacitance measured in

A

Farads

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38
Q

What is the time required for a capacitor to attain full charge proportional too and what causes an increase in time to charge

A

Capacitance and Resistance of the circuit.

  • Increased Resistance increases time to charge
  • Increased Capacitance increases time to charge
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39
Q

Does Capacitors make Amps/Voltage in-phase or out-phase in AC circuit and why

A

Capacitors make Amps/Voltage out of phase due to amps slowing down as voltage rises up

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40
Q

What happens when AC circuit polarity is reversed with a capacitor in the circuit

A

As voltage reverses polarity, the amps is then released from the capacitor

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41
Q

What is the AC resistance in large and small capacitance

A

Low HZ with a Large Capacitor has less resistance

High Hz with a Small Capacitor has less resistance

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42
Q

What is the Capacitive Reactance Formula

A

XC = 1/(2πFC)

XC = Capacitive Reactance in Ohms              
F= Frequency                      
C = Capacity of capacitor in Farads
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43
Q

Does Ohmmeter send its own voltage

A

Yes, If you were to isolate an object to check its continuity you use ohmmeter which tells you if those conductors are connected

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44
Q

What is Capacitance Reactance unit

A

Ohms

45
Q

How do you find total capacitance reactance in series and parallel for AC and DC

A

Series: Summed up for both AC and Dc

Parallel: 1/((1/XC1)+(1/XC2)+(1/…))

46
Q

What is Induced Voltage proportional to in a closed conductor

A

Voltage is proportional to the rate of change of the magnetic flux

47
Q

What is inductance reactance

A

In a circuit a induced magnetic field causes voltage to oppose the circuit only in the inductance or induced area

48
Q

What happens to voltage in an inductance when AC circuit reverse polarity

A

When AC voltage switches polarity, Voltage in the inductance will always be opposite polarity of the the circuit. Also know as inductance reactance

49
Q

What can increase inductance

A

Increasing loops, core material, how close the loops are, and length of inductance

50
Q

What is the inductance units

A

Henries

51
Q

How do you find total inductance in series and parallel in DC and AC

A

Series: Summed inductance
Parallel: 1/((1/L1)+(1/L2)+(1/…))

52
Q

What is the formula for inductance reactance

A

XL=2πFL

                 XL = Inductive Reactance
                 F = Frequency
                 L = Inductance
53
Q

What is inductance reactance unit

A

Ohms

54
Q

How do you find total Resistance of a Resistor, Capacitance Reactance, Inductance Reactance

A

Impedance = square root(Ω^2 + (XL - XC)^2)

55
Q

In impedance what is the order of subtraction

A

The smallest number is always subtracted from the largest number. (You’re never supposed to get a negative)

56
Q

What are Transformers purpose and what are transformers made of

A

To step up and Step down voltage and amps

Transformers are made of inductors

57
Q

What decides whether the transformer is step-up or step-down and what is the loop formula

A

The amount of loops in each inductor

Increased loops increases volts and decreases amps

Decreased loops decreases volts and increases amps

58
Q

What remains the same inside a transformer

A

Watts

59
Q

Are you able to have multiple secondary wiring’s in a transformer

A

yes

60
Q

What ratio is Voltage input and output ratio equal to in a transfomer

A

Ratio of turns;

Turns in primary : Turns in secondary

=

Primary Voltage : Secondary Voltage

61
Q

What current do batteries deliver

A

DC

62
Q

What are common types of batteries

A

Lead Acid, Nickel-Cadmium, Lithium Batteries, Nickel-Metal Hydride

63
Q

What are cells of batteries made of

A

Anodes and Cathodes with electrolyte connecting them

64
Q

How do you charge a battery

A

Provide current into a battery

65
Q

What determines the voltage of a battery

A

Number of cells in series

66
Q

What determines the voltage capacity of a cell

A

Size of Cathode and Anode

67
Q

What creates shortages in lead acid batteries

A

Shed Sulfides can cause shortages between plates if they build up and connect to each other

68
Q

What is the Voltage of a 6 cell lead-acid battery and what is the voltage of one lead-acid cell

A

12.6v and 2.1v

69
Q

Why is there electrolytes in batteries

A

To promote electron flow

70
Q

What is the purpose of bottom below lead acid batteries

A

to allow an area for shed to accumulate

71
Q

What is the specific gravity of water

A

1

72
Q

What creates the flow of electricity in lead acid batteries

A

Lead drops electrons and sulfate accepts them

73
Q

What are the chemicals of Anode, Cathodes, and Electrolytes when a lead acid battery is charged and discharged

A

Charged: Cathode (Lead Dioxide), Anode (Lead), Electrolyte (Concentrated Sulfuric Acid)

Discharged: Cathode (Lead Sulfate), Anode (Lead Sulfate), Electrolyte (Sulfuric Acid)

74
Q

What are sealed batteries advantages

A

Can handle higher temperatures, tolerant at high altitude, and safer

75
Q

What is Charge of constant current

A

Low Amps which is a slow charge

76
Q

What is Charge of Constant Voltage

A

High Amps which is fast charge

77
Q

What chemical do batteries evaporate and why is the chemical dangerous

A

Batteries release hydrogen and the chemical is dangerous because hydrogen is explosive

78
Q

Nickel Cadmium (Nicad) described

A

Low Voltage per cell, Made from Nickel Mesh, uses electrolyte potassium hydroxide

79
Q

Specific Gravity of Nicad battery

A

1.24 - 1.3

80
Q

When can Nicad batteries be serviced

A

When fully charged due to discharge absorbs electrolyte potassium hydroxide, servicing when discharged has risk of overflowing battery when it recharges

81
Q

What remains constant and what is inconstant in parallel and series

A

Parallel: Amps inconstant, Volts constant
Series: Volts inconstant, Amps Constant

82
Q

What neutralizes electrolyte for a lead-acid battery

A

Sodium Bicarbonate

83
Q

What decreases internal resistance in a Nicad Battery

A

Rise in temperature

84
Q

DC Motor Described

A

DC motor is a rotating machine which transforms DC energy into mechanical energy

85
Q

What determines the direction of rotation in a DC motor

A

Current Direction

86
Q

What determines the amount of torque in a DC motor

A

Material, Coil Position, and Strength of coil Magnetic Field

87
Q

When is DC more likely to arc

A

DC is more likely to arc when air density decreases

88
Q

What are the three types of motor wiring

A

Series, Shunt, and Compound

89
Q

Series Wound Motors described and effects

A

The entire motor is series

Series wound motors have high torque when starting out because they have lots of current due to low resistance within them

90
Q

Shunt Wound Motors described and effects

A

Electromagnet on the outside is wired parallel to the loop

Constant torque motor

91
Q

Compound Motor Described and effects

A

Mix of series and shunt

High starting torque and constant torque

92
Q

What is a duty cycle motor

A

A Motor that heats up and requires cooling for a certain period of time before starting again

93
Q

Buffer Logic Gate Described

A

Input = Output

94
Q

Inverter Logic Gate Described

A

Input = Output (Inverted Input)

95
Q

AND Logic Gate described

A

All Inputs must be positive to get a positive output

96
Q

NAND Logic Gate described

A

All Outputs are positive unless all inputs are positive where the output will be negative

97
Q

OR Logic Gate Described

A

If any inputs are positive the output will be positive

98
Q

XOR Logic Gate Described

A

Exclusively Positive output only when not all inputs are the same

99
Q

XNOR Logic Gate Described

A

Exclusively Negative output only when all inputs are negative will you get a positive

100
Q

NOR Logic Gate Described

A

Only when all inputs are negative will an output be positive

101
Q

Semiconductors Defined

A

Conductors or Insulators with impurities that create excessive amount of electrons (N-Type) or create a lack of electrons (P-Type)

102
Q

Diodes Defined and how they work

A

P-Type Semiconductor next to a N-Type semiconductor

Excess Electrons flow from N-Type Semiconductor to lack of electrons in P-Type Semiconductor, which makes P-Type Semiconductor a N-Type net force and N-Type Semiconductor P-Type Net force, which creates a reverse bias. The reverse bias stops current flow due to energy difference. Adding a circuit to a Diode creates a excessive amount of electrons in N-Type Semiconductor and removes electrons from P-Type Semiconductor which removes the net force for both N-Type and P-Type semiconductors allowing for electrons to flow only in one direction.

103
Q

Types of Diodes and Purposes

A

Power Rectifier Diode for high current

Zenner Diode breaks down overtime

Light Emitting diode emits light

Photodiode Senses Light

104
Q

What is the purpose of a rectifier

A

To allow current to flow only in one direction through the circuit

105
Q

How do AC Induction motors work

A

Loop of wire follows a rotating magnetic field

106
Q

How does the magnetic field within the AC Induction motor rotate

A

AC sends current to different inductors over different time which changes the location of the magnetic field allowing for the magnetic field to rotate

107
Q

How does the magnetic field with the three phase AC induction motor rotate

A

Three phase AC is shifted 120° from each other, causing different inductors to activate one after another allowing the magnetic field to rotate

108
Q

What are the advantages of a three phase AC induction motor vs. a regular AC induction motor

A

Three phase AC induction motor is for higher torque and is self starting

109
Q

Eddy Current Defined

A

Stray Electrical current.

General Maintenance (physics, math, and electrical) (3 decks)

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