Basic Concept of Electric Circuit

Subdivision in Electrical Engineering

•Communication systems

•Computer systems

•Control systems

•Electromagnetic

•Electronics

•Photonics

•Power systems

•Signal processing

Electric Current

•The time rate of flow of electrical charge passing through a predetermined area of a conductor.

•The unit is in Ampere [A]

•Constant current of 1[A]=1[C/s]

Fluid Flow Analogy

•Electrical circuits are analogous to fluid flow systems.

•Battery = Pump

•Charge=Fluid

•Conductors (Copper wires)=pipes

•Current=Flow rate of the fluid

•Voltage=Pressure difference between points in the fluid circuit

Switches=Valves

Kirchhoff’s Current Law(KCL)

•A node in an electrical circuit is a point at which two ore more circuit elements are joined together.

•The net current entering a node is zero.

•Current entering---------- (+)

•Current leaving------------ (-)

•I1+I2-I3=0

•Another way to state KCL: The sum of currents entering a node equals the sum of currents leaving a node.

•I1+I2=I3

•No current is lost around the closed circuit

•The sum of the currents at a node must equal to zero