Circuit Elements Notes

Circuit Elements RRB JE & SSC JE Study Notes – An Introduction

Electrical Network: A combination of various electric elements connected in any manner is called an electrical network.

Electrical Circuit

• An electrical circuit is a network which has a closed path that gives the return path for the flow of current.
• Electrical networks can either be closed or open but electrical circuits are only closed
• Hence every electrical circuit is a network, but all networks are not circuits.

Types of Circuit Elements – Notes for SSC JE & RRB JE

Active Element

• The elements that supply energy to the circuit is called an active element
• These have an ability to control the flow of charge
• Used for current control and voltage control applications
• Examples: Battery, voltage source, current source, diode

Passive Element

• The element which receives 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
• Do not need any form of electrical power to operate
• Not able to control the flow of charge
• Cannot amplify, oscillate, or generate an electrical signal
• Used for energy storage, discharge, oscillating, filtering and phase shifting applications
• Examples: Resistor, inductor, capacitor

Go through the table given below to know more about the other circuit elements with examples.

Element	Definition	Examples
Unilateral Elements	These elements allow the conduction of current in only one direction.	Diode, transistor, voltage source
Bilateral Elements	These elements allow conduction of current in both directions with the same magnitude.	Resistance, inductance, capacitance
Linear Elements	A linear element is one whose parameters do not change with voltage or current. It has primarily two properties: homogeneity and additivity.	Resistor, Inductor, Capacitor
Non-Linear Elements	A nonlinear element is that whose parameters change with voltage or current. It does not obey homogeneity and additive properties.	Diode, Transistor

A circuit is linear if and only if its input and output can be related by a straight line passing through the origin otherwise, it is a nonlinear system.

Test your prepartion, right away –

Voltage & Current Source

Ideal Voltage Source: An ideal voltage source has zero internal resistance.

Practical Voltage Source: A practical voltage source consists of an ideal voltage source (V_S) in series with internal resistance (R_S).

An ideal voltage source and a practical voltage source can be represented as shown in the figure.

Ideal Current Source: An ideal voltage source has infinite resistance. Infinite resistance is equivalent to zero conductance. So, an ideal current source has zero conductance.

Practical Current Source: A practical current source is equivalent to an ideal current source in parallel with high resistance or low conductance.

Ideal and practical current sources are represented as shown in the below figure.

Test your prepartion, right away –

Circuit Elements – Open & Short Circuit

Short Circuit: It is an electrical circuit that allows a current to travel along an unintended path with zero or very low electrical impedance. This results in an excessive amount of current flowing into the circuit.

Ideally, it has zero resistance hence high current will flow and no voltage drop across the terminals.

Open Circuit: It is a circuit where no current flows. Any circuit which does not have a return path to flow current is an open circuit.

It has infinite resistance, hence no current will flow.

Short circuit and an open circuit can be represented as shown in the figure.