Part 1: The Theory of Electrical Networks

In the realm of electrical engineering and circuits, wires are used for the conduction/flow of electricity. These wires together form a network, which is difficult to read when multiple components are used in the same circuit.

Introduction

To get started with Electronics, it is foremost important to understand the nature of electricity. You can understand it’s analogy with river-stream from this Blog. Once the concept is imaginative and clear, you might want to understand how it used in the circuits that we see in the form of schematics and PCBs.

Since flow of electricity is determined by the voltage and current, in this article we will delve into the concept of voltage polarity, the direction of current flow, and the relationship between power and energy absorption or emission in active and passive elements.

Voltage Polarity:

Voltage can be classified into two categories: positive and negative. Positive voltage (+V) refers to the potential difference from a point of lower electric potential to a point of higher electric potential.

Conversely, negative voltage (-V) represents the potential difference from a point of higher electric potential to a point of lower electric potential. The polarity of voltage is essential when analyzing the behavior of components within a circuit.

Direction of Current Flow:

The flow of electric charges, or current (I), is influenced by the voltage (V) present in a circuit. The direction of current flow is conventionally assumed to be from positive to negative, known as conventional current flow. This convention was established before the understanding of electron behavior, which actually moves from negative to positive, known as electron flow. However, regardless of the chosen convention, the analysis and calculations in circuits remain consistent.

Active and Passive Elements:

Active and passive elements are fundamental components in electrical circuits that interact with voltage and current in different ways —

Active elements, such as batteries, generators, and transistors, have the capability to generate or supply energy to a circuit. These elements are typically sources of electrical power, as they can provide a voltage difference (ΔV) and deliver current (I) to other components.

Passive elements, such as resistors, capacitors, and inductors, do not generate energy but rather store or dissipate it. These elements rely on the external power sources, such as batteries or generators, to provide the necessary voltage for their operation. Passive elements can either absorb energy or emit energy depending on their characteristics and the overall circuit configuration.

Energy Emission and Absorption:

The rate at which energy is absorbed or stored is also defined as power and can be calculated using the same formula:

P = IV

When an active element it emits or abosrbs energy to/from the load or other components connected in the circuit. This energy transfer is usually accompanied by a power dissipation (P). This dissipation will be positive or negative depending on it’s type.

Passive elements primarily absorb energy from the circuit or store it temporarily, therefore it has Positive(+ve) Power Dissipation.

Active component, a source of power such as an electric generator or battery, will have Negative(-ve) Power Dissipation.

I will explain Power Dissipation concept, on demand someday.

Next Steps:

After understanding what electricity can do with elements, we should next look into the different theorems and practices used to make circuits. Few of them are listed below, you can check them out based on the numbering -

1. Series & Parallel Combinations
2. Superposition & Homogeneity
3. Thevenin & Norton
4. Maximum Power Transfer
5. Reciprocity Theorem
6. Compensation Theorem
7. Millman’s Theorem
8. Tellegen’s Theorem
9. Substitution Theorem
10. Miller’s Theorem

This article is further continued in the PART 2: The Theory of Electrical Wiring blog. You can proceed for detailed information on them.

Conclusion:

Understanding voltage polarity and the direction of current flow is crucial in analyzing and designing electrical circuits.

Active and passive elements interact with voltage and current differently, either supplying or absorbing energy. Power (P), which represents the rate of energy transfer, is a key concept that helps us quantify the energy flow in a circuit.

By comprehending these fundamental principles, engineers and electricians can effectively work with electrical systems, ensuring their proper functioning and optimization.

See you in the next part :)