Electric Circuit: Definition, Types, Components and Working Principle

Electric circuits are all around us, from the lights in your room to the buzzing sound of your phone charging. Everything works because of a simple flow of electric current. Have you ever wondered how these tiny components connect to make electricity move so smoothly?

Imagine electricity travelling like water through pipes; it needs a clear path, the right tools, and proper connections to flow. This article helps learners to understand what an electric circuit is, the symbols used for its components, and how these components work together to allow current to flow safely and efficiently. 

Table of Contents

• What is an Electric Circuit?
• Types of Electric Circuits
• How a Simple Electric Circuit Works?
• Important Components of an Electric Circuit
• Basic Formulas of Electric Circuit
• Electrical Safety Tips Everyone Should Know

What is an Electric Circuit?

An electric circuit is a closed pathway made of wires and components that lets electric current flow. This is the basic electric circuit definition that helps us understand everything from glowing bulbs to running appliances.

In simple words, we can define an electric circuit as,

“ It is a collection of elements designed in such a way that they carry electric current in a certain direction. ”

Here is one simple electric circuit diagram for your reference. 

In the above electric circuit diagrams, we can see that the electric bulb is connected to the battery through connecting wires. 

Here, when we connect only one end of the battery to the bulb, the bulb does not glow because the circuit is not complete. But when we connect both ends of the battery to the bulb, the circuit is closed, and the bulb lights up. Interesting! This shows that electric current flows only in a complete (closed) circuit.

If the connections in a circuit are loose, it can cause a fire. An electrical fire should never be put out with water because it can cause an electric shock.

Here, you might have wondered how a simple wire and battery can make a bulb glow.

An electric circuit works only when there is a closed loop, like a complete circle, connecting the positive end to the negative end of the battery. That is the simplest type of circuit. 

But imagine opening a television! Inside, you would find a huge, complicated circuit with many tiny parts all working together. Electric circuits can be as simple as a bulb or as advanced as a TV!

Types of Electric Circuits

A circuit is a path through which electric current flows, and there are several types based on how the components are connected:

1. A circuit in which the switch is open, and the current does not flow, is called an open circuit. The image below shows an example of an open circuit.

2. A circuit in which the switch is closed and the current flows through the circuit is called a closed circuit. 

3. A short circuit happens when electric current takes a shorter, unwanted path instead of the normal path. This can be very dangerous. Short circuits can lead to overheating, and sometimes the electrical system may even catch fire. The image below shows a fire caused by a short circuit.

4. When all the resistors or components are connected one after another in a single path, it is called a series circuit. The image below shows a series circuit.

5. When all the resistors or components are connected side by side, giving multiple paths to flow, it is called a parallel circuit. The image below shows a parallel circuit.

Read More: Types of Circuits

How a Simple Electric Circuit Works?

A simple circuit has four main parts: a power source, conductors, a switch, and a load. Let's have a look at the simple circuit diagram below for better understanding. 

In the above circuit diagram, we can see that, 

• A cell is the power source that provides energy to the circuit.
• A Load, which is also called a resistor. It is usually a bulb that glows when the circuit is complete.
• Conductors are copper wires without insulation. One wire connects the power source to the load, and the other wire connects the load back to the power source.
• A switch creates a small gap in the circuit. It can open or close the circuit, allowing the current to stop or flow.

Important Components of an Electric Circuit 

Every part of an electric circuit is shown using a special symbol. These symbols make circuit diagrams easy to understand without writing long descriptions. 

The diagram below shows the common symbols used in an electric circuit, including a cell, battery, switch, bulb, and connecting wires and so on.

• Open switch: Symbol that shows the circuit is broken and current cannot flow.
• Closed switch: Symbol that shows the circuit is complete and current can flow.
• A fuse is a safety device that protects the circuit by melting if too much current flows.
• A battery is a group of cells joined together to supply electrical energy.
• A cell is a single source of electrical energy in the circuit.
• A Voltmeter is an instrument used to measure the voltage across components.
• An Ammeter is a device used to measure the current flowing in the circuit.
• A buzzer is a component that produces sound when current passes through it.
• A lamp/bulb converts electrical energy into light energy when current flows.
• A resistor is a component that restricts the flow of current in the circuit. 

Read More: Circuit Diagram & Its Components

Now we know what an electric circuit is, its components and what it looks like. There are several important formulas used in electric circuits. So let's discuss them in our next section.

Basic Formulas of Electric Circuit

To understand how electric circuits work, it is very important to be familiar with the basic formulas used in calculations. The table below presents the basic formulas of an electric circuit, along with their symbols, meanings, and SI units. 

Topic	Formula	Notations	Units
Electric Current	I=Qt	I = current,  Q = charge,  t = time	Ampere (A)
Voltage (Ohm’s Law)	V = I × R	V = Voltage,  I = current,  R = resistance	Volts (V)
Resistance	R=ρ×(lA)	R = resistance,  ρ = resistivity,  l = length,  A = cross-sectional area	Ohm (Ω)
Power	P = V × I or    P=Et	P = power,  E = energy, t = time	Watt (W)
Conductivity	σ=1ρ	σ=conductivity, ρ = resistivity	Siemens per meter (S/m)
Capacitance	C=QV	Q = charge,  V = Voltage	Farad (F)
Series Resistance	Req=R1+R2+...+Rn	Req = total resistance in series,    R1,R2...Rn= individual resistors	Ohm (Ω)
Parallel Resistance	1Req=1R1+1R2+...+1Rn	Req= total resistance in parallel,    R1,R2...Rn= individual resistors	Ohm (Ω)

Electrical Safety Tips Everyone Should Know

You might have seen danger signs on electric poles, transformers, or even on some home appliances. 

These signs warn us that electricity can be very dangerous if not handled properly. It can even cause serious injury or death. That is the reason why electric wires, sockets, and live wires must always be covered and kept away from children.

You may wonder after knowing that, a small battery has a very low voltage, usually less than 12 volts, but a transformer can have a very high voltage, sometimes up to 11,000 volts! 

We have learned that electric current flows only when there is a complete and unbroken path from the battery, through the components, and back to the battery. If the circuit is broken anywhere, the current stops immediately.

Batteries must also be handled with care. You should never connect the two terminals of a battery directly without a bulb or any load. This makes the chemicals inside the battery react very quickly and release a lot of energy, which can even make the battery burst.

So far, we have learnt that electric circuits are an essential part of our everyday life, whether it’s a glowing bulb, a charging phone, or a running fan. By now, you know that an electric circuit works only when there is a complete and unbroken path for current to flow.