This document provides an introduction to fundamental concepts of electric circuits. It defines key elements like sources, resistors, capacitors and switches. It explains concepts such as voltage, current, Kirchhoff's laws, and Ohm's law. It also describes different types of circuits including series, parallel and combinations. Divider rules for voltage and current are introduced to analyze circuits.

1. Fundamentals
Of
Electric circuits

2. INDEX
 Introduction
 Principal Elements
 Voltage And Kirchhoff’s Voltage Law (KVL)
 Current And Kirchhoff’s Current Law (KCL)
 Types Of Circuits
 Resistance And Ohm’s Law
 Voltage Divider Rule (VDR)
 Current Divider Rule (CDR)
 Superposition Theorem

3. INTRODUCTION
 “An Electric Circuit is an interconnection of
electrical elements.” There are many elements
used in an circuit:
1. Sources
2. Branch & Node
3. Loop & Mesh
4. Resistor
5. Inductor
6. Capacitor
7. Switch
8. Wire

4. DEPENDENT SOURCE:
1. Dependent Sources are whose input (current or
voltage) is a function of some other voltage or
current in a circuit.
2. The symbols typically used to represent
dependent sources are in the shape of a
diamond.

5. INDEPENDENT SOURCE:
1. Independent Sources have the capability of
generating a prescribed voltage or current
independent of any other element within the
circuit.
2. These sources may output constant
voltage/current that varies with time.

6. BRANCH & NODE
 Branch is any portion of
circuit with two terminals
connected with it. It may
consist of one or more
circuit elements.
 Node is the point of
connection between two
or more branches. A
node usually indicated
by a dot in a circuit.

7. LOOP & MESH
 Loop is any closed path
through the circuit in
which no node is
encountered more than
once.
 Mesh is a loop that does
not contain any other
loops.

8. VOLTAGE & KVL
 Voltage is the total work per unit charge associated
with the motion of charge between two points. The
unit of voltage is Volt (v).
 Kirchhoff’s Voltage Law (KVL) states that, “The net
voltage around a closed circuit is zero.” This
means, algebraic sum of the potential rises and
drops around a closed loop or path is zero.

9. CURRENT & KCL
 Current is defined as the time rate of change of
charge passing through a predetermined area. The
unit of electric current is called Ampere (A).
 Kirchhoff’s Current Law (KCL) states that, “The
sum of the currents at a node must equal to
zero.” That means, the algebraic sum of current
entering and leaving a node is equal to zero.
or

10. RESISTANCE & OHM’S LAW
 An ideal Resistor is a device that exhibits
linear resistance properties according to
Ohm’s Law, which states that, “The voltage
across a resistance is directly
proportional to the current flowing
through it.”
V = IR
where R is resistance, whose unit is
measured
in Ohm.

11. TYPES OF CIRCUIT
 Open Circuit: A circuit
element whose
resistance approaches
infinity.
 Short Circuit: A circuit
element whose
resistance approaches
zero.

12. SERIES CIRCUIT
 Two or more circuit elements are said to be
in Series if the current from one element
exclusively flows in to the next elements. All
series elements have the same current and
there is only one common point between two
elements.

13. PARALLEL CIRCUIT
 Two or more circuit elements are said to be
in Parallel if the elements share the same
terminals. All parallel elements have the
same voltage and there is more than one
common point between two elements.

14. VOLTAGE DIVIDER RULE
 VDR is useful in determining the voltage drop
across a resistance within a series circuit.
Where,
VX = the voltage drop across the measured resistor,
RX = the voltage drop across the measured resistor,
REQ = the circuit total resistance,
VS = the circuit applied voltage

15. CURRENT DIVIDER RULE (CDR)
 CDR is useful in determining the current flow
through one branch of a parallel circuit.
where,
IX = the current flow through any parallel branches,
RX = the resistance of the branch through the
current is to be determined,
REQ = the total resistance of the parallel branch,
IS = the circuit applied current