INDEPENDENT AND DEPENDENT SOURCES

Independent Sources 

Voltage sources 

A two-terminal element is called an independent voltage source if it maintains a prescribed voltage across the terminals of the arbitrary circuits to which it is connected.

Current sources

A two-terminal element is called an independent current source if it maintains a prescribed current into the arbitrary circuits to which it is connected.

Dependent Sources

A voltage or current source whose source (controlled) variable depends on some other voltage or current in the network (i.e. the controlling variable.

CIRCUITS ELEMENT

Passive Element

• components that absorbs energy.
• current will enter from positive to negative.

Active Element

• components that supply or shearing energy.
• current will going out from positive to negative.

DEFINITION (ELECTRICAL CIRCUITS)

Voltage

An electromotive force or potential difference expressed in volts.
Is the electric potential difference between two points or the difference in electric potential energy of a unit test charge transported between two points. greater the voltage, the greater the flow of electrical current.

unit ~ volts ( V )
symbol ~ V

V = IR 

V = W/Q

Current

Current is flow of electrical charge carriers.
One ampere of current represents one coulomb of electrical charge (6.24 x 10¹⁸ charge carriers) current are flow from relatively positive points to relatively negative points; this is called conventional current or Franklin current.

each electron = 1.602 x 10^-19 coulombs ( C )

unit ~ ampere ( A )
symbol ~ I

 I = V/R

 I = dQ/dt

Charge

Electrical charge is an electrical property of matter that exists because of an excess or deficiency of electrons.

unit ~ coulombs ( C )
symbol ~ Q

Power

Electrical power is the rate at which electrical energy is converted to another form, such as motion, heat, or an electromagnetic field. or the rate at which electric energy is transferred by an electric circuit.

unit ~ watt ( W )
symbol ~ P

P = VI

P = E/t (watts, W or joules/second, J/s)

Energy

energy is a measure of power expended or used over time.

unit ~ joules ( J )
symbol ~ E or W

W = Pt (wattseconds, Ws or joules,J)