Electricity Flashcards
(109 cards)
1
Q
Formula for Volts, Amps, and Resistance
A
Amps * Ohms
2
Q
What is a side effect of energy loss in resistance
A
Temperature increase
3
Q
What is the purpose of resistors
A
to limit current flow
4
Q
What is ohms/amps/volts Series circuit rules
A
Total Resistance is summed
Amps is equal throughout the circuit
Voltage is summed
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
6
Q
What is Rheostat Resistor
A
Changeable resistance resistor
7
Q
What is a Potentiometer Resistor
A
Changeable resistance resistor
8
Q
What is a Tapped resistor
A
Resistor separator
9
Q
What is a Thermo-resistor
A
Changeable resistor by temperature
10
Q
What is a Photo-resistor
A
Changeable resistor by light
11
Q
Tolerance defined
A
The range of a product that can be higher or lower (+ or -)
12
Q
Ohms/Amps/Volts Parallel Circuit Rules
A
Amps are not constant
Voltage is constant
Total Resistance is lower then the lowest resistance
13
Q
Formula for Parallel Resistance
A
1/((1/R1)+(1/R2)+(1/…))
14
Q
What is a battery rating
A
Sum of the batteries voltage
15
Q
one HP equals how many watts
A
746 watts
16
Q
Watts Formula
A
Watts = Amps * Volts
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
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)
19
Q
How do Amp, Ohms, and Volt meters added to a circuit
A
Ammeter is series
Voltmeter is parallel
Ohmmeter is isolated series
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
21
Q
Open Circuit Defined
A
Incomplete circuit
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
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
24
Q
AC Defined
A
electricity that constantly changes direction and intensity
25
When can magnets induce electricity on a conductor
Only when the conductor is perpendicular to the lines of flux
26
What does a magnetic field induce on a conductor
Only voltage constantly and a current only is created when the conductor is being induced or removed from induction
27
Define Cycle and Frequency
Cycle is repetition of the sine wave pattern
Frequency is cycles per second
28
Define Phase Relationships, In-Phase, or Out-Phase
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
29
Instantaneous Value Defined
The amp value or voltage value at a certain degree and time
30
Define Capacitors
Short term energy storage unit, that releases charge when pressure is released in the circuit
31
What prevents arcing in a capacitor
Dielectric
32
Why do capacitors stop current
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
33
What are the three factors that create resistance in a AC circuit
Resistors, Inductive Reactance, Capacitive Reactance
34
What increases the amount of electrons a Capacitor can hold
Plate area, Spacing of Dielectric, Dielectric Material
35
What causes the capacitor limit to be exceeded
If Voltage is to high he dielectric breaks down and arcing occurs
36
What is the formula for capacitance in series and Parallel
Series: 1/((1/C1)+(1/C2)+(1/...))
Parallel: Sum
37
What is capacitance measured in
Farads
38
What is the time required for a capacitor to attain full charge proportional too and what causes an increase in time to charge
Capacitance and Resistance of the circuit.
- Increased Resistance increases time to charge
- Increased Capacitance increases time to charge
39
Does Capacitors make Amps/Voltage in-phase or out-phase in AC circuit and why
Capacitors make Amps/Voltage out of phase due to amps slowing down as voltage rises up
40
What happens when AC circuit polarity is reversed with a capacitor in the circuit
As voltage reverses polarity, the amps is then released from the capacitor
41
What is the AC resistance in large and small capacitance
Low HZ with a Large Capacitor has less resistance
High Hz with a Small Capacitor has less resistance
42
What is the Capacitive Reactance Formula
XC = 1/(2πFC)
```
XC = Capacitive Reactance in Ohms
F= Frequency
C = Capacity of capacitor in Farads
```
43
Does Ohmmeter send its own voltage
Yes, If you were to isolate an object to check its continuity you use ohmmeter which tells you if those conductors are connected
44
What is Capacitance Reactance unit
Ohms
45
How do you find total capacitance reactance in series and parallel for AC and DC
Series: Summed up for both AC and Dc
Parallel: 1/((1/XC1)+(1/XC2)+(1/...))
46
What is Induced Voltage proportional to in a closed conductor
Voltage is proportional to the rate of change of the magnetic flux
47
What is inductance reactance
In a circuit a induced magnetic field causes voltage to oppose the circuit only in the inductance or induced area
48
What happens to voltage in an inductance when AC circuit reverse polarity
When AC voltage switches polarity, Voltage in the inductance will always be opposite polarity of the the circuit. Also know as inductance reactance
49
What can increase inductance
Increasing loops, core material, how close the loops are, and length of inductance
50
What is the inductance units
Henries
51
How do you find total inductance in series and parallel in DC and AC
Series: Summed inductance
Parallel: 1/((1/L1)+(1/L2)+(1/...))
52
What is the formula for inductance reactance
XL=2πFL
XL = Inductive Reactance
F = Frequency
L = Inductance
53
What is inductance reactance unit
Ohms
54
How do you find total Resistance of a Resistor, Capacitance Reactance, Inductance Reactance
Impedance = square root(Ω^2 + (XL - XC)^2)
55
In impedance what is the order of subtraction
The smallest number is always subtracted from the largest number. (You're never supposed to get a negative)
56
What are Transformers purpose and what are transformers made of
To step up and Step down voltage and amps
Transformers are made of inductors
57
What decides whether the transformer is step-up or step-down and what is the loop formula
The amount of loops in each inductor
Increased loops increases volts and decreases amps
Decreased loops decreases volts and increases amps
58
What remains the same inside a transformer
Watts
59
Are you able to have multiple secondary wiring's in a transformer
yes
60
What ratio is Voltage input and output ratio equal to in a transfomer
Ratio of turns;
Turns in primary : Turns in secondary
=
Primary Voltage : Secondary Voltage
61
What current do batteries deliver
DC
62
What are common types of batteries
Lead Acid, Nickel-Cadmium, Lithium Batteries, Nickel-Metal Hydride
63
What are cells of batteries made of
Anodes and Cathodes with electrolyte connecting them
64
How do you charge a battery
Provide current into a battery
65
What determines the voltage of a battery
Number of cells in series
66
What determines the voltage capacity of a cell
Size of Cathode and Anode
67
What creates shortages in lead acid batteries
Shed Sulfides can cause shortages between plates if they build up and connect to each other
68
What is the Voltage of a 6 cell lead-acid battery and what is the voltage of one lead-acid cell
12.6v and 2.1v
69
Why is there electrolytes in batteries
To promote electron flow
70
What is the purpose of bottom below lead acid batteries
to allow an area for shed to accumulate
71
What is the specific gravity of water
1
72
What creates the flow of electricity in lead acid batteries
Lead drops electrons and sulfate accepts them
73
What are the chemicals of Anode, Cathodes, and Electrolytes when a lead acid battery is charged and discharged
Charged: Cathode (Lead Dioxide), Anode (Lead), Electrolyte (Concentrated Sulfuric Acid)
Discharged: Cathode (Lead Sulfate), Anode (Lead Sulfate), Electrolyte (Sulfuric Acid)
74
What are sealed batteries advantages
Can handle higher temperatures, tolerant at high altitude, and safer
75
What is Charge of constant current
Low Amps which is a slow charge
76
What is Charge of Constant Voltage
High Amps which is fast charge
77
What chemical do batteries evaporate and why is the chemical dangerous
Batteries release hydrogen and the chemical is dangerous because hydrogen is explosive
78
Nickel Cadmium (Nicad) described
Low Voltage per cell, Made from Nickel Mesh, uses electrolyte potassium hydroxide
79
Specific Gravity of Nicad battery
1.24 - 1.3
80
When can Nicad batteries be serviced
When fully charged due to discharge absorbs electrolyte potassium hydroxide, servicing when discharged has risk of overflowing battery when it recharges
81
What remains constant and what is inconstant in parallel and series
Parallel: Amps inconstant, Volts constant
Series: Volts inconstant, Amps Constant
82
What neutralizes electrolyte for a lead-acid battery
Sodium Bicarbonate
83
What decreases internal resistance in a Nicad Battery
Rise in temperature
84
DC Motor Described
DC motor is a rotating machine which transforms DC energy into mechanical energy
85
What determines the direction of rotation in a DC motor
Current Direction
86
What determines the amount of torque in a DC motor
Material, Coil Position, and Strength of coil Magnetic Field
87
When is DC more likely to arc
DC is more likely to arc when air density decreases
88
What are the three types of motor wiring
Series, Shunt, and Compound
89
Series Wound Motors described and effects
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
Shunt Wound Motors described and effects
Electromagnet on the outside is wired parallel to the loop
Constant torque motor
91
Compound Motor Described and effects
Mix of series and shunt
High starting torque and constant torque
92
What is a duty cycle motor
A Motor that heats up and requires cooling for a certain period of time before starting again
93
Buffer Logic Gate Described
Input = Output
94
Inverter Logic Gate Described
Input = Output (Inverted Input)
95
AND Logic Gate described
All Inputs must be positive to get a positive output
96
NAND Logic Gate described
All Outputs are positive unless all inputs are positive where the output will be negative
97
OR Logic Gate Described
If any inputs are positive the output will be positive
98
XOR Logic Gate Described
Exclusively Positive output only when not all inputs are the same
99
XNOR Logic Gate Described
Exclusively Negative output only when all inputs are negative will you get a positive
100
NOR Logic Gate Described
Only when all inputs are negative will an output be positive
101
Semiconductors Defined
Conductors or Insulators with impurities that create excessive amount of electrons (N-Type) or create a lack of electrons (P-Type)
102
Diodes Defined and how they work
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
Types of Diodes and Purposes
Power Rectifier Diode for high current
Zenner Diode breaks down overtime
Light Emitting diode emits light
Photodiode Senses Light
104
What is the purpose of a rectifier
To allow current to flow only in one direction through the circuit
105
How do AC Induction motors work
Loop of wire follows a rotating magnetic field
106
How does the magnetic field within the AC Induction motor rotate
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
How does the magnetic field with the three phase AC induction motor rotate
Three phase AC is shifted 120° from each other, causing different inductors to activate one after another allowing the magnetic field to rotate
108
What are the advantages of a three phase AC induction motor vs. a regular AC induction motor
Three phase AC induction motor is for higher torque and is self starting
109
Eddy Current Defined
Stray Electrical current.
