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Electrical Engineering
GLOSSARY OF TERMS MECHANICS FUNDAMENTALS
Conductor Material which permits electrons to flow freely NEWTON’S LAWS OF MOTION
Couple Two equal and opposite parallel forces that
are applied to the same body Law I Bodies will continue in uniform motion unless acted
upon by external forces
Dielectric Insulating material between capacitor plates; Law II The rate of change of a body’s linear momentum is
capacitance increases by numerical factor, k proportional to, and in the direction of, force applied
(dielectric constant) • F = ma
Electric Measure of the opposition that an electric
Impedance circuit presents to the flow of current when Law III Forces of action and reaction between bodies are equal
voltage is applied in magnitude, opposite in direction, and collinear
Electromagnetic Oscillations of the inductor’s magnetic CONDITIONS OF EQUILIBRIUM
Oscillation field and the capacitor’s electric field
EMF Device Works on charges to maintain a potential • Static equilibrium occurs when the resultants of all external forces
difference between output terminals acting on a body are zero
Equipotential Adjacent points on a surface with the same Equilibrium Equations
Surface electric potential; electric field is always
perpendicular to equipotential surfaces Note: Equations are for planar, 2-dimensional, and 3-dimensional
Ferromagnetic Substance in which magnetization persists rigid body statics
Material after the field has been removed
• Vector relationships for a force system: ∑ F = 0 and ∑ M = 0
Force Vector action of one body on another • Written as components along x-, y-, and z-axes, relationships
Hysteresis Residual magnetism that is left when the become ∑ Fx= 0, ∑ y = 0, ∑zF = 0, x M = 0, y M = 0, and
material (such as iron) is slowly demagnetized ∑ Mz= 0
Inertia An attribute of bodies implying capacity to GEOMETRY OF MOTION
resist changes of motion
Insulator Material that impedes conductance of • In mechanics, kinematics is the study of the motions of bodies as
electricity a function of time
Integrated Complete circuit is contained in a single piece Linear All points of a body follow congruent paths
Circuit of semiconductor material Rotational Paths circle about an axis; velocity and acceleration
Magnetic Simplest magnetic structure (such as a bar are proportional to the radius
Dipole magnet) where net magnetic flux is zero
w Mesh In circuit analysis, a loop that has no loop in Harmonic Body moves back and forth about a position at rest
Oscillation (amplitude represents maximum deflection)
w its interior Base Derivatives of Kinematics
Momentum An attribute that is proportional to the mass
w and velocity of a body Velocity ds Where s represents distance and
Open Circuit Path for current flow between 2 points is v = dt t represents time
. broken
p
e Phasor A vector that rotates around an origin Angular dφ Where f represents the angle
Principle In a circuit network, a node (junction) with Velocity ω = dt
r Node three or more branches
m
Reactance Circuit property with capacitance and Angular a =d ω Where w represents angular velocity
inductance Acceleration dt
a Rectification Changing AC to DC by blocking the reverse
c flow of a charge
MOMENTS OF INERTIA
h Resonance An oscillation of a system at its natural • Define the relationship between the area or mass of a body and
a frequency
Semiconductor Material that is not conductive nor insulating the position of a line
r • Moment of inertia of a figure = sum of moments of its parts
t Shearing Force In mechanics, a force acting parallel to a Area Moments of Inertial, I (Statics)y
plane Measuring 2
s Short Circuit Path for current flow between two points has the distribution A dx y∫ A
. zero impedance 2 x dA
c Stress In mechanics, the measure of internal forces of area about an axiA dy x∫
r y
o of a body between particles resisting A dz r∫ 2
separation 0 x
m Superconductor Material that presents no resistance to the
movement of electric charge Mass Moments of Inertia, I (Dynamics)
Torque Turning force or twisting moment Measuring the moment of inertia dm
of a volummmdIrr= ∑ =2 ∫
Torsion Torque applied in planes perpendicular to
body’s axis r
Transformer Electromagnetic device with 2 or more
mutually coupled windings; it can raise and
lower voltage in a circuit
1 ELECTRICAL ENGINEERING • A-816-8 © 1996-2011 Mindsource Technologies Inc. l e a r n • r e f e r e n c e • r e v i e w
permachartsM
ELECTROSTATICS CIRCUIT BASICS
ELECTRIC CHARGE, Q Circuits Made up of active and passive elements and their interconnecting
conducting paths
Elementary Charge Active Include sources such as batteries, DC generators, AC generators, and so on
• Charge is not fluid; it consists of multiple
elementary charges Elements
• Any charge q can be written as q = ne, Passive Include current controlling devices such as resistors, capacitors, inductors,
where n = positive or negative integer and Elements and so on
e = elementary charge
Note: e has a value of 1.602 ¥ 10C CIRCUIT ANALYSIS & DESIGN
Electric Current
(coulomb)
Electrostatic Force Current The rate at which electricity flows
Magnitude Depends on electromotive force (potential difference) and dimensions of
• The charge on any body is measured in
relation to the force between two charges path through which it circulates
Force: Proportional to the product of the Ohm’s Law I = V/R, where I is the current, V is the electrical potential difference, and
two charges; inversely proportional to the R is the resistance
square of the distance between them
Potential Difference (Electromotive Force, EMF)
Coulomb’s Law • In the case of direct current, Ohm’s law defines potential difference as the product of
• Relates force, quantity of charge, and current and resistance; commonly used as a measure of the strength of a source of
distance of separation such that force electric energy (EMF); here, V = IR
between 2 electric charges is p2oportional Resistance
to product of22 charges ÷ distancer • Resistance is passive elements in circuits which control current and the degree to which
F = q1 2/4πed Newtons
a material resists the flow of current
ELECTRIC FIELD, E • Used to control flow of current through a circuit; here, R = V/I
Resistivity
• Charged particles alter their surrounding
space • Resistivity is property of a material determines its conductivity
• The electric field (or field intensity) can be • To calculate resistance from resistivity, R = pl/A, where p is the resistivity of the material,
l is the length, and A is the area
found at a point by imagining a particle of
charge at rest and measuring the electric
force F acting upon it; KIRCHHOFF’S LAWS
E = electrostatic force / charge
• According to Gauss’ Law, the total electric Current Law Total current flowing into any node in a circuit equals the total current
flux of a closed surface in an electric field is flowing away from that node • The algebraic sum of the currents
proportional to the sum of the electric entering any node is zero • ∑ I = 0
charges within the surface Voltage Law In a closed circuit, sum of potential drops equals resultant EMF in the
loop • The algebraic sum of the potential difference around any closed
• Capacitance (C) is the property of an
element which opposes changes in circuit is zero • ∑ V = 0
voltage, as given by the equation q = CV, m
where q is the charge and V is the THEVENIN’S THEOREM NORTON’S THEOREM
potential difference o
• A network of sources and resistors at a • A network of sources and resistors at a
• A capacitor consists of two isolated pair of terminals can be replaced with pair of terminals can be replaced by a c
conductors (plates) with equal and opposite a series combination of a voltage parallel combination of a current source .
charges (+q, -q) separated by a dielectric source and resistor and resistor s
t
r
SELECTED QUANTITIES & UNITS a
Base Quantities Common Quantities h
Quantity Symbol Unit Unit Symbol Quantity Symbol Unit Unit Symbol c
Length L, l meter m Charge Q, q coulomb C a
Mass M, m kilogram kg Current I, I ampere A
m
Time T, t second s Potential difference volt V
Electric current I ampere A Power P, p watt W r
e
Temperature Kelvin K Work/Energy W, w joule J
Luminous intensity candela cd Resistance R ohm Ω p
Plane angle radian rad Conductance ∑ siemens S .
Solid angle steradian sr Capacitance C farad F w
Magnetic flux F weber Wb
Constants w
Magnetic field B tesla T
Constant Symbol Value Force F Newton N w
Elementary charge e 1.60 ¥ 1019C
-11 2 2 Flux density B tesla T
Gravitational constant G 6.67 ¥ 10 Nm /kg Inductance L henry H
Permittivity constant e 8.85 ¥ 1012F/m
6 Frequency ƒ hertz Hz
Permeability constant µ0 1.26 ¥ 10 H/m Angular frequency w radians/second rad/s
Electron mass m e 9.11 ¥ 1031kg
Proton mass m 1.67 ¥ 1027kg Electromotive force EMF volt V
p
2 ELECTRICAL ENGINEERING • A-816-8 © 1996-2011 Mindsource Technologies Inc. l e a r n • r e f e r e n c e • r e v i e w
permachartsM
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