Electrical Engineering Basics And Formulas
The basic things of Electrical engineering is called fundamentals(electrical components).
- Electric charges.
- Electric current and voltage.
- Electrical circuit Elements.
- Fundametal laws electric engineering.
Electrical Charges is the physical property of the matter,The main cause is due to force experience
by the two closed electical charged particles.
The force exerted by one charge q on another charge Q is givern by colomb’s law.
coulmb’s law F= (kqQ/r^2)
Whrere, constant k=8.99*10^9Nm^2/c^2.
r-> is the distance between two charges.
SI UNIT OF CHARGE : Coulomb (C)
Material are divided into three according to the how easily charge( ie electons) to flow along them.
Conductors – (eg: Metals)
Semi-condutors – (eg: Silicon)
Insulators – (eg: Rubber,wood,platic)
Electric Current and Voltage
The rate flow of charges in a condutor is called current.The electric current i is givern by,
Current (i) =Q/t
where Q charge in coulomb and t charge flowing time in seconds.
SI UNIT OF CURRENT : Ampere (A)
“The flow of one coulomb of charge in one second is one unit electric current.”
a) Direct Current(DC): The flow charges is in always in one direction and steady for the period of
contstant time is known as Dc.
b) Alternating Current(AC):Name indicates likes its alternating.The flow of charges first in one direction
then the other direction repeating this cycle in definite freequency is known as AC.
current flow through electrical element when a voltage appears acroos the terminals of the element
just like whater flows through a pipe when pressure differnce appears acroos the pipe.
SI UNIT OF VOLTAGE : Volt(V)
Electic Power and Energy
The work done or energy transferred in an electric circuit wih a voltage V is givern VQ Where Q is the charge moved through the circuit in a given time t . hence power
Power (p) = Vq/t or V*(q/t) P= VI
Where I is current
SI UNIT OF POWER : Watt(W)
cappacity to doing work is called Energy.
Energy (E) = VIT
SI UNIT OF ENERGY : Joule(J)
Electrical circuit Element
Componnents of electric circuit are called circuit elements.The circuit element may be active and passive elements. There are Three types of passive elements ressistors,capacitorand inductor.
The oppostion of to the passage of an electric current through the conductor.It is the property is most
commonly described by Ohme’s law states that “the voltage acorss the resistor is dirctly proportional to
the cuurent at constant temperature and pressure”.
Resistance (R) = V/I
SI UNIT OF RESISTANCE : ohm
series conection : Rs=R1+R2+…..
parallel connection: Rp=1/R1+1/R2……
Capacitor is charge storing device.Capacitor allso called condenser.It an electric device consisting of two
conductors sepearted by an insulating dielectric medium.The raio of on one of the condutors of the capacitor to the potential differnce between two condutor is called capacitance
Capacitance (C) = Q/V
SI UNIT OF CAPACITANCE : Fard
Its allso a charge storing device .It stores maganetic energy.
Inductance (I) = L*(di/dt)
Where L self inductance
SI UNIT OF INDUCTANCE : Henry