1.0 Fundamentals of Electric Circuits

8/6/2019 1.0 Fundamentals of Electric Circuits

http://slidepdf.com/reader/full/10-fundamentals-of-electric-circuits 1/12

Lectures on ECEN 3054 Electric Circuit 1

Kaycee B. Victorio

Department of Electrical Engineering

Polytechnic University of the Philippines



Basic concepts on

SI Units

Electric charge and current

Voltage, power and energy Dependent sources and other circuit elements

Resistance

Inductance

Capacitance Passive and active circuit elements



Term Definition SI Unit

Current any movement of

electric charge

carriers

Ampere, A, is the constant

current which, if maintained in

two straight parallel

conductors of infinite length of

negligible circular cross sectionand placed 1 m apart in a

vacuum, would produce

between these conductors a

force equal to 2 × 10-7 N/m

Chargebasic property of matter

carried by some

elementary particles; can

be positive or negative,

occurs in discrete natural

units and is neither

created nor destroyed

Coulomb, C, is defined as thequantity of electricity

transported in one second by a

current of one ampere




Resistance property of an

electric circuit or

part of a circuit

that transforms

electric energy intoheat energy in

opposing electric

current

Ohm, Ω, is equal to the

resistance of a circuit in which

a potential difference of one

volt produces a current of one

ampere

Inductance property of a conductor

that is measured by the

size of theelectromotive force, orvoltage, induced in it,

compared with the rate

of change of the

electric current that

produces the voltage

Henry, H, is the value of self-

inductance in a closed circuitor coil in which one volt is

produced by a variation of the

inducing current of one

ampere per second




Capacitance property of an electric

conductor, or set of

conductors, that is

measured by the

amount of separatedelectric charge that

can be stored on it per

unit change in

electrical potential

Farad, F, when one coulomb of

electricity changes the

potential between the plates

by one volt

Voltage the amount of work

needed to move aunit charge from a

reference point to a

specific point

against an electric

field

Volt, V, is equal to the

difference in potentialbetween two points in a

conductor carrying one ampere

current when the power

dissipated between the points

is one watt.



Term Definition SI Units

Power time rate of doing

work or delivering

energy

Watt, W, is the

power dissipated in

an electrical

conductor carrying

one ampere currentbetween points at

one volt potential

difference

Energy the capacity for

doing work

Joule, J, is equal to

the work done by aforce of one newton

acting through one

meter



Type Definitions SI Units

Conductance (G) the readiness with

which a conductor

transmits an electric

current expressed as

the reciprocal of electrical resistance

Siemens, S, is the

reciprocal of the

resistance in ohms

Admittance (Y) the reciprocal of the

impedance of a

circuit

Siemens, S, is the

reciprocal of the

resistance in

impedanceFrequency the number of cycles

or vibrations

undergone during

one unit of time by a

body in periodic

motion

Hertz, Hz, a unit of

frequency equal to

one cycle per second




Force (F) any action that tends

to maintain or alter

the motion of a body

or to distort it

Newton, N, is defined as

that force necessary to

provide a mass of one

kilogram with an

acceleration of one metre

per second per second

Magnetic flux (ø) region in the

neighbourhood of a

magnet, electric

current, or changing

electric field, in

which magnetic

forces are observable

Weber, W, the amount of

flux that, linking an

electrical circuit of one

turn (one loop of wire),

produces in it an

electromotive force of one

volt as the flux is reducedto zero at a uniform rate in

one second

Magnetic flux density

(B)

measure of the actual

magnetic field within a

material considered as a

concentration of magnetic

field fluxes, per unit cross-sectional area

Tesla, T, is equals to

one weber per

square metre



Is the path for transmitting electric

current. An electric circuit includes

a device that gives energy to the

charged particles constituting the

current, devices that use current

and the connecting wires or

transmission lines.



Element Definitions

Passive circuit element or

passive element

Circuit element that takes energy from

the sources and either convert it

another form or store it in electric or

magnetic field

Active circuit element or

active element

Circuit element that is able to supply

energy to the network

Independent source Energy source in the circuit that is not

affected by the changes in the

connected circuit

Dependent source Energy source in the circuit that isaffected by the changes in the

connected circuit



Dependent voltage and current sources are depicted below with adiamond shaped terminal (b) and (d). Independent sources are (a) and(c). Passive elements resistance (e), inductance (f) and capacitance (g).



End of discussion

Fundamentals of electric circuit

ECEN 3054 Network Analysis 1

Documents

1.0 Fundamentals of Electric Circuits