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1. Basic Circuit Elements :
Introductory Concepts
Prepared by
Dr. Arindam Sen
Asst. Professor, Dept. of Electronics
Bankura Christian College

2. • An electric circuit is an interconnection of electrical elements (e.g. batteries, resistors, capacitors, inductors,
switches etc.) linked together in a closed path so that electric current may flow continuously
• A circuit element cannot be broken down or subdivided into other circuit elements
• A circuit element can be defined in terms of the behavior of the voltage and current at its terminals
Electrical Network/Circuit ?

3. Circuit Elements
Linear and Non-Linear Element
• A Linear element shows linear characteristics of voltage vs current. e.g. resistor, capacitor, inductor
• Resistance, capacitance and inductance does not change with a change in applied voltage or the circuit
current.
• When the current passing through an element does not change linearly with the linear change in applied
voltage at a particular frequency, it is called Non-Linear element.
• Semiconductor devices are usually Non-Linear.

4.  Active and Passive Elements
• The elements that supply energy to a circuit is called active element. In other words, if a circuit element has the capability of enhancing the
energy level of a signal passing through it, it is called an active element.
• Examples of active elements include voltage and current sources, generators, and Vacuum tubes and semiconductor devices (such as
transistor, op-amp etc.)
• A transistor is an active circuit element, meaning that it can amplify power of a signal. On the other hand, transformer is not an active
element because it does not amplify the power level and power remains same both in primary and secondary sides.
• The element which receives energy (or absorbs energy) and then either converts it into heat (R) or stored it in an electric (C) or magnetic (L
) field is called passive element.
• Resistors, inductors, capacitors are examples of Passive elements
Circuit Elements

5. Unilateral and Bilateral Elements
• If the magnitude of the current passing through an element is affected due to change in the polarity of the
applied voltage, the element is called Unilateral element. e.g. diodes, transistors etc.
• If the current magnitude remains the same even if the applied emf’s polarity is changed, it is called a Bilateral
element. e.g. resistors, capacitors, inductors etc.
• Unilateral elements offer varying impedances with variation in flow of current while Bilateral elements offer
same impedance irrespective of flow of current.
Circuit Elements

6. Classification of Circuit
 Linear Circuit
 It is the circuit whose parameters remain constant with change in applied voltage or current
 More specifically, a linear system is one that satisfies (i) homogeneity property and (ii) additive property
Fig. 1 I-V Characteristic of a Linear Circuit Fig. 2 I-V Characteristic of a Non-Linear Circuit
 Non-Linear Circuit
• It is a circuit whose parameters change with voltage or current
• More specifically, non-linear circuit does not obey the homogeneity and additive properties.

7.  Unilateral Circuit
• When the direction of current is changed, the characteristics or properties of the circuit may change
 Bilateral Circuit
• When with change in direction of current, the characteristics or properties of the circuit may not change, it is called a Bilateral circuit
 Active Circuit
• It is a circuit which contains one or more than one sources of emf
 Passive Circuit
• When the circuit does not contain any source of emf, it is called passive circuit
 Lumped and Distributed Circuit
• Physically separate circuit elements like R, L or C are known as Lumped elements. A Transmission Line or a cable is an example of Distributed circuit as
throughout the line, they are not physically separate
• If the circuit is fabricated with its elements in lumped form, it is called a Lumped circuit and if in distributed form, it is called Distributed circuit.
 Recurrent and Non-recurrent Circuit
• When a large circuit consists of similar networks connected one after another, the circuit is called as Recurrent Circuit or Ladder circuit. On the other hand, a
single circuit is called Non-recurrent circuit
Classification of Circuit

8. Look at the interconnection
Fig. 3 A Simple Resistive Circuit

9. Basic Definition of few Important Terms
• Node- A node in an electric circuit is an equipotential point where two or more components are connected together. This
point is usually marked with dark circle or dot.
• Junction – It is that point of a network where three or more circuit elements are joined. The circuit in fig. 3 has 4 junctions - a,
b, c, and g.
• Branch- It is a part of a circuit that lies between junction points. Fig.3 shows that the circuit has six branches: three resistive
branches and three branches containing voltage and current sources.
• Loop- A loop is any closed path in an electric circuit. Fig. 3 shows three loops or closed paths namely, a-b-g-a; b-c-g-b; and
a-c-b-a. Further, it may be noted that the outside closed paths a-c-g-a and a-b-c-g-a are also form two loops.
• Mesh- A mesh is a special case of loop that does not have any other loops within it or in its interior. Fig. 3 indicates that the
first three loops (a-b-g-a; b-c-g-b; and a-c-b-a) just identified are also ‘meshes’ but other two loops (a-c-g-a and a-b-c-g-a)
are not.

10. Determine the number of junctions, branches,
loops, meshes and nodes in the circuit shown

11. THANK YOU