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Electrical Engineering > Basic Electrical Terms, Concepts, Formula, And Units > Flashcards

Basic Electrical Terms, Concepts, Formula, And Units Flashcards

1
Q

Voltage (formula)

A

W= QE

W= work in Joules
Q= charge in Columb
E= electric potential or voltage in Volts
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2
Q

Current (formula)

A

Q= It or dq= idt

Q= charge in columb
I= current in Amperes
t= time in seconds
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3
Q

Power (formula)

A

P= VI or P=I²R or P= V²/R

P= power in watts
V= voltage in volts
I= current in amperes
R= resistance in ohms
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4
Q

Resistance (formula)

A

RA= ρL

R= resistance in Ohms 
A= cross sectional area in m²
ρ= resistivity of a given length and cross sectional area of a certain material, normally measured at 20° C reference temperature in Ω-m
L= length in meters
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5
Q

Resistance in drawing process (formula)

A

RV= ρL² or RA²=ρV

R= resistance in Ohms 
A= cross sectional area in m²
ρ= resistivity of a given length and cross sectional area of a certain material, normally measured at 20° C reference temperature in Ω-m
L= length in meters
V= volume of wire in m³
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6
Q

Insulation Resistance of an Insulated cable (formula)

A

2πLR=ρIn(r1/r2)

R= resistance in Ohms
r1= bigger radius in meters
r2= smaller radius in meters
ρ= resistivity of insulator in Ω-m
L= length in meters
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7
Q

Temperature effect οn resistance (formula)

A

R2(T+t1)=R1(T+t2) or R2=R1{1+αt1(t2-t1)}

R1= resistance @ temperature t1
R2= resistance in temperature t2
T= inferred absolute zero temperature
α= temperature coefficient of resistance, α(t)=1/(T+t)
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8
Q

A Coulomb is equal to ______ electrons or protons.

A

1C = 6.25x10¹⁸ electrons or protons

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9
Q

1 watthour is equal to _____ Joules

A

1Wh = 3600J

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10
Q

1 horsepower is equal to ______ watts

A

1Hp = 746W

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11
Q

1 mil is equal to _____ inch

A

1 mil = 0.001 in.

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12
Q

1 CM is equal to ____ square mil

A

1 CM = π/4 square mil

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13
Q

Anything that occupies space and has mass

A

Matter

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14
Q

A substance that cannot be decomposed any further by chemical action

A

Element

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15
Q

Smallest part that an element can be reduced to and still keeping the chemical properties of the element

A

Atom

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16
Q

Combination of two or more elements

A

Compound

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17
Q

It is the smallest particle that a compound can be reduced to before it breaks down into its elements.

A

Molecule

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18
Q

Negatively charged particles that revolve around the nucleus of an atom

A

Electrons

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19
Q

Mass of an electron

A

About 9.11x10-³¹ kg

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20
Q

Maximum number of electron in a given shell (formula)

A

N=2n²

N= total number of electron in a given shell
n= nth shell of the atom
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21
Q

Positively charged particles that stay in the nucleus of an atom

A

Protons

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22
Q

Mass of a proton

A

1.673x10-²⁷ kg

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23
Q

Particles having no charge

A

Neutrons

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24
Q

Mass of a neutron

A

1.675x10-²⁷ kg

25
Q

The central part of the atom where the protons and neutrons are located at the __________.

A

Nucleus

26
Q

Represents the number of electrons and protons of an element

A

Atomic number

27
Q

Represents the sum of protons and neutrons of an atom

A

Atomic mass

28
Q

Electrons found in the outermost shell or orbit of an atom

A

Valence electrons

29
Q

Materials having less than four valence electrons

A

Conductors

30
Q

Materials having four valence electrons

A

Semi-conductors

31
Q

Materials having more than four valence electrons

A

Insulators

32
Q

Unit of electric charge

A

Coulomb (C)

33
Q

Unit for electric charge is named after __________.

A

Charles A. Coulomb (French physicist, 1736-1806)

34
Q

One electron or proton has a charge of ______ coulombs

A

1.6x10-¹⁹ C (reciprocal of 6.25x10¹⁸ electrons or protons per charge)

35
Q

A body is said to be charge if

A

It has either an excess or deficit of electron from its normal values due to sharing

36
Q

Any charge has the capability of doing work of moving another charge either by __________ or ____________.

A

Attraction or repulsion

37
Q

When a potential difference between two charges forces a third charge to move, the change in motion is called a/an __________.

A

Electric current (denoted as I)

38
Q

The capacity to do work

A

Energy (usually denoted as W)

39
Q

The net number of electorns moved in the direction of the positive charge depend upon the ________ between the two charges.

A

Potential difference (denoted as E or V)

40
Q

Unit of potential difference

A

Volts (V)

41
Q

Unit of potential difference is named after ____________.

A

Alessandro C. Volta (Itallian physicist, 1754-1827)

42
Q

Who invented the first electric battery?

A

Alessandro C. Volta¹ & John Stringfellow² (1799 or 1800)

43
Q

Unit of charge flow

A

Ampere (A)

44
Q

Unit of charge flow is named after

A

Andre M. Ampere (French physicist and mathematician, 1775-1836)

45
Q

Property of material that opposes or resist the flow of electrons

A

Resistance (denoted as R)

46
Q

Unit for resistance

A

Ohm (Ω)

47
Q

Practical unit of resistance is named after ________.

A

Georg S. Ohm (German physicist, 1787-1854)

48
Q

The amount of change of resistance in a material per unit change in temperature

A

Specific resistance or resistivity

49
Q

Area of a circle having a diameter of one mil

A

CM or circular mil

50
Q

Resistance of a given length and cross sectional area of a certain material

A

Resistivity (ρ)

51
Q

Resisitivity of a material is normally measured at _____ reference temperature.

A

20°C

52
Q

The reciprocal of resistance

A

Conductance (denoted as G)

53
Q

Unit for conductance

A

Siemens (S)

54
Q

When conductors undergo drawing process, the material is assumed negligible (100% efficiency), thus keeping the ________ to be constant all throughout the process.

A

Volume

55
Q

For conductors udergoing drawing process, the resistance varies __________ of the length.

A

Resistance varies directly as the square of the lenght

R2/R1 = (L2/L1)²

Subscript 1= before drawing process
Subscript 2= after drawing process

56
Q

For conductors undergoing drawing process, the resistance varies ________ of the diameter.

A

Resistance varies inversely as the fourth power of the diameter.

R2/R1 = (d1/d2)⁴

Subscript 1= before drawing process
Subscript 2= after drawing process

57
Q

Resistance if all wires generally used in practice of electrical systems ___________ as the temperature increases.

A

Increases

58
Q

Ohmic change per degree at some specific temperature

A

Temperature coefficient of resistance (denoted as α)

59
Q

Temperature coefficient formula @ temp t (formula)

A

αt = 1/(T + t)

αt= temperature coeeficient @ temp t
T= inferred temperature
t= temperature

Electrical Engineering (2 decks)

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