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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

What is the unit that represents the value of a Color Coded Inductor?

MICRO Henrys (μH)