Flashcards in Electrical Elements Deck (158):
1
What does a wire gauge represent?
the diameter of the entire wire, bigger gauge number, smaller diameter and vice versa
2
What are the common gauge numbers used in households?
10AWG - 5.261mm^2
12AWG - 3.309mm^2
14AWG - 2.081mm^2
3
Superconductor is also known as?
Cryogenic conductor
4
What material is the best conductor of electricity?
Silver, due to most number of free electrons per unit volume
5
which metals are the best conductors of electricity
Pure silver
Pure copper
Pure gold
Aluminum
6
What are wire-wound resistors?
Uses metal alloys that are independent of temperature like manganin and constantan, and have an inductive property
7
What are thin film resistors
Deposited thin metal(Ceramic Metal) on an insulating support, Has High Resistance, Has no Reactive property
8
What are carbon composition resistors?
low wattage fixed type made from carbon, Its size is proportional to the power it can handle
9
What is a rheostat?
variable resistor with only two terminals, used in high power and high voltage, wire-wound(has inductive property)
10
What is potentiometer
variable resistor used for low power and low current application, has 3 terminals
11
Resistors color code
1st significant, Second Significant, multiplier, tolerance,
Black Black 0
Boys Brown 1
Respect Red 2
Our Orange 3
Young Yellow 4
Girl Green 5
But BLue 6
Violeta Violet 7
Goes Gray 8
White White 9
12
What does the reliability (5th) band in a resistor indicate?
Reliability (in percent of failure per 1000 hours of use)
13
It is the fundamental source of electrical energy developed through the conversion of chemical or solar energy
Cell
14
Combination of two or more cells
Battery
15
These are not rechargeable cells, AND DO NOT HAVE RESISTANCE
Primary Cell
16
These are rechargeable cells AND HAVE RESISTANCE
Secondary Cells
17
Two common rechargeable cells
Lead-Acid used in automobiles
Nickel-Cadmium used in calculators/tools/photoflash units
18
Carbon-zinc (Leclanche): Classification and output voltage
Primary/1.5V designed for 70 degrees Farenheit operation
19
Zinc Chloride: Classification and output voltage
Primary/1.5V Heavy Duty type
20
Manganese Dioxide (alkaline): Classification and output voltage
Primary or Secondary/ 1.5V has low internal resistance
21
Mercuric Oxide: Classification and output voltage
Primary/1.35V
22
Silver Oxide: Classification and output voltage
Primary 1.5V
23
Lead Acid: Classification and output voltage
secondary 2.1V
24
Ni-Cd: Classification and output voltage
Secondary 1.25V
25
Nickel-Iron(Edison Cell): Classification and output voltage
Secondary 1.2V
26
Nickel-Metal hydride: Classification and output voltage
Secondary 1.2V, does not suffer memory effect
27
Silver-Zinc: Classification and output voltage
Secondary 1.5V
28
Silver Cadmium : Classification and output voltage
Secondary 1.1V
29
Battery Life expression
Battery Life(Hr)=Ampere-Hour rating(Ah)/Amperes Draws
30
Also called as Crowfoot cell/gravity cell/wet cell used in operating telegraphs and door bells
Daniel Cell
31
Also called as galvanic Cell, Named after Luigi Galvani
Voltaic Cell
32
Primary Cell with high output voltage, long shelf life, low weight and small and can provide 10x more energy
Lithium Cell
33
Very good power to weight ratio, often found in high end laptop
Lithium-ion battery
34
Used in electric vehicles
Metal-chloride battery
35
Other name for a capacitor
Condenser
36
Unit of capacitance is named after?
Michael Faraday
37
What is the reciprocal of capacitance?
Elastance, unit is daraf
38
What is Gauss Theorem
The total electric flux extending from a closed surface is equal to the algebraic sum of the charges inside the closed surface
39
Gauss Theorem mathematical Expression
ψ = Q
Wb(Unit of flux) = C(unit of charge)
ψ - # Electric Flux Lines
Q - Charges inside an enclosed surface
40
Electric Flux Density Formula
D=ψ/Area
where: ψ=total flux, Mx or Wb
A=Area, cm^2 or m^2
1 Tesla= 1Wb/m^2
1 Gauss = 1 Maxwell/cm^2
41
Electric Field Intensity Formula
E=F/Q
F= Newtons,
Q=Charge, Coulomb
in capacitors:
E=V/d
where V=voltage, d=plate separation
42
First law of Electrostatics
unlike charges attract each other while like charge repel each other
43
Second law of elecrostatics
the force of attraction or repulsion between charges is directly proportional to the product of the two charges but inversely proportional to the square of distance between them
44
Second law of statics mathematical formula
F = kq1q2/r^2
k=1/(4π*εo*εr)
εo=absolute permittivity, shift constant 32
45
What is permittivity?
It is the ratio of electric flux density to the electric field strength
ε=D/E (in Farads/m)
46
relative permittivity (εr) of teflon
2.0
47
relative permittivity (εr) of paper, paraffined
2.5
48
relative permittivity (εr) of mica
5.0
49
relative permittivity (εr) of transformer oil
4.0
50
It is the voltage required per unit length to establish conduction in a dielectric
Dielectric Strength or breakdown voltage
51
Dielectric strength of Air
75 V/mil
OR
3 x 10^6 (V/m)
52
Dielectric strength of Barium-strontium titanite(ceramic)
75 V/mil
OR
3 x 10^6 (V/m)
53
Dielectric Strength of transformer oil
400 V/mil
54
Formula for the energy stored in a capacitor
Wc=1/2*CV^2 or Q^2/2C
55
What is the electrical definition of capacitance?
Charge per unit volt
C=Q/V
Q=charge
V=Voltage
56
Formula for capacitance based on physical construction
C=(n-1)*(εA/d)
n=number of parallel plates
ε=permittivity
A=plate area
d=distance bet. plates
57
Series Capacitor's total capacitance
Ct = 1 / ( {1 / C1} + {1 / C2} + ....)
58
Total charge in a series capacitor
Qt=Q1=Q2=Q3
59
Identical capacitors in series total capacitance
Ct=C/n
60
Total capacitive reactance on series capacitors
Xct=Xc1+Xc2+Xc3..
61
Parallel Capacitor Total capacitance
Ct= C1 + C2 + C3
62
Parallel Capacitor identical capacitors capacitance
Ct = nC
63
Parallel Capacitor total charge
Qt=Q1+Q2+Q3...
64
Parallel Capacitor capacitive reactance
Xct = 1 / ( {1/Xc1{ + {1/Xc2} + {1/Xc3} )
65
capacitance of parallel-plate capacitor (with multiple dielectrics in between)
C = εoA / ( [d1/εr1] + [d2/εr2] + [d3/εr3] )
d1,d2,d3 - dielectric thickness within the parallel plates
εr1, εr2, εr3 - Relative Permittivity of the dielectrics
66
Cylindrical capacitor formula
C = [ (εr*l) / (41.4log(b/a)) ] x10^-9
a=inner diameter of single core cable conductor
b=outer diameter
l=length of the cylindrical capacitor
67
Capacitance of an isolated Sphere
C=4*π*ε*r
r=radius of isolated sphere
68
Capacitance of concentric sphere, out sphere is grounded
C=4*π*ε(ab/(b-a))
a=inner radius
b-outer radius
69
Capacitance of concentric sphere, inner sphere is grounded
C=4*π*ε*b^2/(b-a)
a=inner radius
b-outer radius
70
It is a measure of the ability of a coil to oppose any change in current through the coil. and store energy in the form of magnetic field
Self Inductance/inductance
71
Formula of inductance in terms of physical dimensions
L=(μ)n^2A/l
μ=permeability of the core, H/m
N=number of turns
A=area of core, m^2
l-mean length of the core
72
Formula of inductance in terms of electrical definition
L= Hd(Φ)/di
73
Energy stored by an inductor
Wl=0.5*L*(I^2)
74
What is faraday's law
The voltage induced across a coil of wire equals the number of turns in the coil times the rate of change of magnetic field
Einductor = Nd(Φ)/dt = Ldi/dt
75
What is lenz's law?
An induced voltage effect is always such as to oppose the cause that produced it
76
Lenz's law mathematical expression
Einductor = - N*d(Φ)/dt
77
Series inductors without mutual inductance
Lt=L1+L2+L3..
78
Series inductors with mutual inductance
M=k*sqrt( L1 * L2 )
Lt(aiding) = L1 + L2 + 2M
Lt(opposing) = L1 + L2 - 2M
k-coupling coefficient
k = 0 if minimum(Blocked by Dielectric)
k = 1 if maximum(Uses Iron Core)
79
Parallel inductors total inductance, aiding
Lt(aiding)=(L1*L2 - M^2) / (L1 + L2 - 2M)
80
Parallel inductors total inductance, opposing
Lt(opposing)=(L1*L2 - M^2) / (L1 + L2 + 2M)
81
Inductance of long coil
L=(μ)N^2*A/l
82
Inductance of short coil
L=(μ)N^2*A/(l+.45d)
d - diameter of short coil
83
Inductance in Toroidal coil with rectangular cross section
L=(μ)(N^2h / 2π) * ln (d2 / d1)
h=thickness, m
d2,d1=outer and inner diameters respectively
L - in μH
84
Inductance of Circular Air core
L=0.07(RN)^2/(6R+9l+10b)
R=d/2+b/2
d=core diameter,in
b=coil buildup,in
l = coil thickness, in
L - in μH
85
Inductance of magnetic core coil, no air gap
L = 0.012N^2(μ)A /lc
A - Area in cm^2
lc - magnetic path length (cm)
L - in μH
86
Inductance of magnetic core coil, air gap
L = 0.012N^2*A /(lg + lc/(μ))
A - Area in cm^2
lc - magnetic path length (cm)
lg - gap length(cm)
L - in μH
87
The unit of electrical power is named after>
James Watt
88
Equivalent power (in watts) of 1 HP
1HP=746W
89
Millman's Theorem
the voltage across the parallel combination is the ratio of the algebraic sum of currents to the internal conductance
90
Power transfer efficiency
n=Rl/(Rl+Rsource)x100%
91
Inferred Absolute Zero Temperature of Copper
T(iazt) = -234.5 °C
92
Inferred Absolute Zero Temperature of Silver
T(iazt) = -243 °C
93
When a Conductor is cooled to the Inferred Absolute Zero Temperature, its resistance is __________
zero
94
Resistivity of Copper (ρ20 in R = ρL/A)
ρ20 = 1.7 x 10^-8 Ω-meters
95
Resistivity of Silver (ρ20 in R = ρL/A)
ρ20 = 1.5 x 10^-8 Ω-meters
96
Resistivity of Gold (ρ20 in R = ρL/A)
ρ20 = 2.4 x 10^-8 Ω-meters
97
Resistivity of Aluminum (ρ20 in R = ρL/A)
ρ20 = 2.6 x 10^-8 Ω-meters
98
Thermistors are usually used as ______
Sensors
99
Thermistors are either _____ or ______
PTC, NTC
100
In a Light Dependent Resistor, its resistance is (Directly/Inversely) Proportional to the illumination on the device
Inversely
101
When does the resistance of a Light Dependent resistor reach maximum value?
When Completely Dark
102
What do you call the maximum resistance of a Light Dependent Resistor?
Dark Resistance
103
In a Voltage Dependent Resistor, its resistance is (Directly/Inversely) Proportional to the Voltage Across the device
Inversely
104
Voltage Dependent Resistors are usually used for _________
Circuit Protection
105
The Cross Sectional Area of a conductor assumed by the unit of Circular Mil looks like a _____
Square ¯\_(ツ)_/¯
CM = d^2
d - diameter of cable
106
The Cross Sectional Area of a conductor assumed by the unit of Square Mil looks like a ______
Circle ¯\_(ツ)_/¯
SM = (π/4)*CM
= (π/4)*d^2
d - diameter of cable
107
Mil is short for ______
Milli-inch (1 x 10^-3)
108
When 4th Band of a resistor has no color, what is the Tolerance%? And the tolerance Letter Designation?
+- 20% (M)
109
When 4th Band of a resistor has the color Brown, what is the Tolerance%? And the tolerance Letter Designation?
+- 1% (F)
110
When 4th Band of a resistor has the color Red, what is the Tolerance%? And the tolerance Letter Designation?
+- 2% (G)
111
When 4th Band of a resistor has the color Green, what is the Tolerance%? And the tolerance Letter Designation?
+- 0.5% (D)
112
When 4th Band of a resistor has the color Blue, what is the Tolerance%? And the tolerance Letter Designation?
+- 0.25% (C)
113
When 4th Band of a resistor has the color Violet, what is the Tolerance%? And the tolerance Letter Designation?
+- 0.1% (B)
114
When 4th Band of a resistor has the color Gold, what is the Tolerance%? And the tolerance Letter Designation?
+- 5% (J)
115
When 4th Band of a resistor has the color Silver, what is the Tolerance%? And the tolerance Letter Designation?
+- 10% (K)
116
When 4th Band of a resistor has the color Gray, what is the Tolerance%? And the tolerance Letter Designation?
+- 0.05% (A)
117
When 5th Band of a resistor has the color Brown, what is the Reliability?
1%
118
When 5th Band of a resistor has the color Red, what is the Reliability?
0.1%
119
When 5th Band of a resistor has the color Orange, what is the Reliability?
0.01%
120
When 5th Band of a resistor has the color Yellow, what is the Reliability?
0.001% (MOST RELIABLE)
121
When the 3rd Band of a resistor is Gold, What is the Multiplier used?
x 10^-1
122
When the 3rd Band of a resistor is Silver, What is the Multiplier used?
x 10^-2
123
When the 3rd Band of a resistor is Pink, What is the Multiplier used?
x 10^-3
124
The property of a battery that determines how efficient its quantity of storage is
Ampere-Hour (AH) efficiency
125
Formula for AH Efficiency(η)
η(AH) = AH(discharge) / AH(charge)
η(AH) = I(d)*t(d) / I(c)*t(c)
I(d) and I(c) - Discharging/Charging Current
t(d) and t(c) - Discharging/Charging time
126
The property of a battery that determines how efficient its storage of Energy is
Watt-Hour Efficiency (WH)
127
Formula for WH(Watt-Hour) Efficiency(η)
η(WH) = WH(discharge) / WH(charge)
η(WH) = P(d)*t(d) / P(c)*t(c)
η(WH) = [ V(d)*I(d)*t(d) ] / [ V(c)*I(c)*t(c) ]
but η(AH) = I(d)*t(d) / I(c)*t(c)
---------------------------------------------
Therefore: η(WH) = η(AH) * (V(d) / V(c))
---------------------------------------------
V(d) and V(c) - Discharging/Charging Voltage
P(d) and P(c) - Discharging/Charging Power
I(d) and I(c) - Discharging/Charging Current
t(d) and t(c) - Discharging/Charging time
128
What does Temperature resistance coefficient of a material describe?
When temperature increases by 1 °C, the resistance increases by (Temperature resistance coefficient) Ohms
129
Temperature resistance coefficient (α20) of:
Gold
3.7 x 10^-3 ( /°C)
130
Temperature resistance coefficient (α20) of:
Silver
3.8 x 10^-3 (/°C)
131
Temperature resistance coefficient (α20) of:
Copper
3.93 x 10^-3 ( /°C)
132
Temperature resistance coefficient (α20) of:
Aluminum
4 x 10^-3 ( /°C)
133
Temperature resistance coefficient (α20) of:
Nichrome
0.4 x 10^-3 (/°C)
134
Temperature resistance coefficient (α20) of:
Manganin
0.03 x 10^-3 ( /°C)
135
Temperature resistance coefficient (α20) of:
Constantan
0.008 x 10^-3 ( /°C)
136
Relative Permittivity (εr) of rubber
3
137
Relative Permittivity (εr) of Pyrex
5.6
138
Dielectric Strength (V/m) of Teflon
60 x 10^6 (V/m)
139
Dielectric Strength (V/m) of Rubber
27.55 x 10^6 (V/m)
140
Dielectric Strength (V/m) of Paper
16 x 10^6 (V/m)
141
Dielectric Strength (V/m) of Mica
197 x 10^6 (V/m)
142
Dielectric Strength (V/m) of Pyrex
14 x 10^6 (V/m)
143
Capacitor Color Coding
Same as Resistance color coding
Although, for 4th Band Tolerance :
Green is 5% in capacitors, not like 0.5% in resistors
Grey is 80%-20% in capacitors
White is 10% in capacitors
Red is 2% in capacitors
yellow is 3% in capacitors
(No reliability)
144
When reading capacitance values, the unit represented by a colored/numbered code is in ___________
PICO farads (pF)
145
Capacitor Number Coding
Capacitor Nimber Coding contain 4 characters:
Char. 1 and 2, are the 1st and 2nd digit of capacitance value
Char. 3 is the multiplier
Char 4 is the Letter Designation for Tolerance(Same as Resistor)
146
Capacitor Number Coding:
When 3rd Char is equal to 0, the multiplier used for the capacitance is:
1 pF
147
Capacitor Number Coding:
When 3rd Char is equal to 1, the multiplier used for the capacitance is:
10
148
Capacitor Number Coding:
When 3rd Char is equal to 2, the multiplier used for the capacitance is:
100
149
Capacitor Number Coding:
When 3rd Char is equal to 3, the multiplier used for the capacitance is:
1000
150
Capacitor Number Coding:
When 3rd Char is equal to 4, the multiplier used for the capacitance is:
10,000
151
Capacitor Number Coding:
When 3rd Char is equal to 5, the multiplier used for the capacitance is:
100,000
152
Capacitor Number Coding:
When 3rd Char is equal to 6 or 7, the multiplier used for the capacitance is:
N/A
153
Capacitor Number Coding:
When 3rd Char is equal to 8, the multiplier used for the capacitance is:
0.01
154
Capacitor Number Coding:
When 3rd Char is equal to 9, the multiplier used for the capacitance is:
0.1
155
Alternative Formula for Mutual Inductance(Given aiding and opposing inductance)
M = (Lta - Lto) / 4
Lta -Total aiding Inductance
Lto - Total opposing Inductance
156
Inductance of Rectangular Air core
L = 0.07*(CN)^2 / (1.908C + 9l +1 0b)
C= d + Y + 2b
d=core hole length,in
Y=core hole width, in
b=coil buildup,in
l = coil thickness
L - in μH
157
Inductor Color Coding
Same as Resistor( 1st, 2nd, Multiplier, Tolerance)
158