You’ve installed various types of lights around your business, and you flip a switch to light a light bulb. Have you ever wondered what happens when you flip a switch and the bulb starts glowing? When you flip the light bulb’s switch, the electrical circuit is forced into action that eventually lights the light bulb. This is what happened! So, today we are going to know about the concept of an electrical circuit.

## What Is Electrical Circuit?

An electrical circuit is a combination of components that can transmit electricity. Simple electrical circuits have conductors (usually wires), a component that supplies energy known as a source (such as a battery or a wall plug), and a component that absorbs electrical energy and can convert to another energy called load. A light bulb can be an example of a load and must always have a return path so that electrons have a way to return to the source of that electrical circuit. Each circuit is designed to supply electrical power to one or more loads. For example, in a boombox, the power goes to the speakers. Likewise, the power of the lamp goes to the bulb. The circuit allows the charge to leave one side of the power supply and return to the other side.

## How Does an Electrical Circuit Work?

From the above discussion, we can say an electrical circuit is a combination of electrical components. An electrical circuit consists of batteries, resistors, inductors, capacitors, switches or transistors. The electrical network consists of a closed-loop. A circuit is a closed path where electrons flow through a wire. As long as the copper wire allows, electrons will flow between the atoms, but they will never leave the copper.

However, when we connect this copper wire to the battery, the free electrons will be driven to the positive pole of the battery. This driving force is called the electromotive force (EMF). E.M.F. expressed in volts. And it’s normally called voltage. As a result of this voltage, an electron moves. This motion is known as current. The current can be measured by connecting an ammeter between the copper wire and the voltage source.  A complete circuit is an infinite loop of electrons. If we take a wire and wrap it around it, it creates a continuous current through which electrons can flow forever. This is the basic concept of the electrical circuit.

## Different Parts of an electrical circuit

Electrical circuits are important concepts that have practical applications in our daily lives. It’s a very simple concept with three distinct components – a source of electrical energy, a device, and a close loop of conductive material.

### (a) Source of Electrical Energy

The first component in the circuit is the source of electrical energy that allows the electrons to move. This source can be a battery, a solar cell, or a hydroelectric power plant—a place with positive and negative electrodes, where the charge can flow from one place to another. The push of this charge is called voltage, and its potential is measured in volts.

### (b) Device in the Electrical Circuit

The second component is the device. It responds to the current passing through it. Today, a device is something that can be plugged into a wall outlet and used with electricity. The loop is usually closed with a piece of conductive material. It’s usually a wire, but there are other kinds of materials that can close the loop. For example, TVs have various metal strips inside that are deposited on a plastic surface, which may be a conductive material, and in some cases, even the chassis of the device becomes part of a closed circuit.

### (c) Resistance of the Electrical Circuit

The third component is resistance; every circuit has some resistance to the flow of electrons. The electrons collide with other electrons and atoms that make up the wire, converting some of the energy into heat. It is simply impossible to transfer energy from one form to another without losing some energy as heat.

### (d) Switch, Fuse, and Circuit Breakers

Flashlights and most other appliances also have switches. A switch is simply a device that helps break a continuous loop of conductive material.

When the switch is open, no current flows, but when the switch is closed, there is current flow. Basically, all circuits work this way. Even in a circuit that is plugged into the wall of a room, there is a continuous loop of wire that runs from your home all the way to the power plant.

Fuses or circuit breakers are used to prevent major fires caused by overloading. If the current is too high, the fuse will burn.

## Types of Electrical Circuit

We can classify electrical circuits from various perspectives. Today I will discuss the classifications periodically.

We know there are two types of current. One is Direct Current and another is Alternating Current. According to the types of current, there are two types of electrical circuits:

(a) DC Circuit: A closed circuit where direct current flows are called a direct current circuit. Current flows in only one direction and is often used in low voltage applications. The resistor is the main part of the DC circuit. Mainly it contains a dc source (Battery), switch and load (Resistor). Also, it may contain measurement equipment like an ammeter, voltmeter and so on. In this circuit load resistor is connected in series, parallel or series-parallel combination as required.

(b) AC Circuit: A circuit excited by an AC source is called an AC circuit. Alternating current (AC) is used for domestic and industrial use. In an AC circuit, the magnitude and direction of the current and voltage are not constant in value but change periodically. It propagates as a sin wave, completing a cycle with positive half and a negative half-cycle and is a function of time (t) or angle (θ=wt). Mainly it contains an ac source (Generator), switch and load (Resistor, Inductor or Capacitor). Also, it may contain other equipment in series, parallel or a combination of series-parallel like a dc circuit.

According to the arrangement of loads, the electrical circuit is classified into three types. These are:

(a) Series Circuit: A series circuit is one that has more than one load, but only a single path through which electricity (electrons) flows. From one end of the source (Generator or Battery, it depends upon AC or DC Circuit), the electrons move along a line without branches, through the load (Resistor, Inductor or Capacitor), to the other end of the source. All components in a series circuit are connected end-to-end, any gaps or disconnections can cause the circuit to fail.

(b) Parallel Circuit: A circuit is called a parallel circuit when two or more components are connected to the same node and both sides of the components are directly connected to the battery or any source. The parallel circuit current has two or more paths through which it passes. In this circuit, if any components fail other components are not affected by this failed component.

(c) Series-Parallel Circuit: If circuit elements are in series in some parts and in parallel in others, we won’t be able to apply a set of rules to every part of the circuit. Instead, we have to determine which parts of the circuit are in series and which parts are in parallel, and then selectively apply the series and parallel rules as needed to determine what’s going on. This type of circuit is known as a series-parallel circuit or combination circuit.

There are three types of electrical circuits according to the value of resistance (For resistive load) or reactance (For inductive or capacitive load) of load:

(a) Closed Circuit: A closed circuit is a complete electrical circuit in which an electric current flows when voltage is applied. It’s like a river crossing bridge. The bridge leaves your car on the road, across the waterway and back to the other side. A closed-circuit allows the flow and movement of electrical energy (electrons). There is no interruption in the flow of energy in a closed circuit.

(b) Open Circuit: An open circuit is a physical break in the conduction path where the current drops to 0 and the resistance becomes infinite (too high for an ohmmeter to measure). But it is possible to measure voltage because the voltmeter is connected to the open terminal. Note that an open circuit is not a true circuit because charges from one side of the power supply cannot leave and return to the other side of the power supply.

(c) Short Circuit: A short circuit is an unintentional low-resistance connection between two or more points in a circuit. Because the current increases with decreasing resistance (given by Ohm’s law), it results in a large amount of current flowing through a “short circuit”. This higher current, if larger than the thickness of the wire, can be introduced high temperature and can cause a fire. This led to the shorting of the circuit Safety devices such as fuses and circuit breakers are used in the event of a short circuit to avoid the risks and associated damage.