What is electrical circuit and why it is so important?

What is electrical circuit | Types of electrical circuit | Close Circuit | Open Circuit | Short Circuit | Series Circuit | Parallel Circuit | Compound Circuit


The most important thing in electrical fields is referred to as an electrical circuit. If we want to transfer power from one place to another, then we have to make a circuit to complete the process. So now we’ll talk about what an electrical circuit is. And why is it so important, and what kind of electrical circuit is it?

What is an electrical circuit?

As we all know, electrical power is used to power a variety of loads. So, to operate the load, we have to make a proper system so that these electrical loads can operate easily. That’s why we make an electrical circuit by using electrical cable and wire. Metal is used to make this wire. The arrangement of wire to operate the load is called the electrical circuit. In this electrical circuit, power flows through the wire in the form of current.

Types of electrical circuits:

Basically, we can classify the electrical circuit into three types.

  1. Close circuit
  2. Open circuit
  3. Short circuit

We will now go over each of the circuit types mentioned above separately.

What is a “closed circuit”?

A closed circuit is a condition of an electrical circuit. Let’s suppose we have a supply source with two terminals (positive and negative). Now suppose that we connect a load to this supply with the help of an on/off switch button. When the switch button is turned off, there is no current flowing through the load. When the switch button is turned on, the current starts to flow through the positive terminal of the supply, goes through the load, and reaches the negative terminal of the supply. In this condition, loading will start operating. Thus, when the current reaches the negative terminal through the load, it means, the circuit is closed. And this condition is called a “close circuit.”

What is electrical circuit
closed circuit

What is resistance and why it is so important?

If you notice this whole action, you will see that some accessories are being used in this system, like a switch, supply sources (AC or DC), and load.

Supply sources:

Supply sources can be two types, like an AC supply source or a DC supply source. This source provides the power to load.


This cable is used to transmit power in the form of current. This is made up of metals like copper, aluminium, steel, etc.

Electrical load:

The washing machine, electrical fan, refrigerator, water heater, room heater, oven, and many more are electrical loads.


A switch is a type of device that turns on and off the load by separating the supply terminals and connecting the terminals, respectively. The MCB is also a switching device, but it protects the electrical load from overload or fault conditions.

What happens when the circuit is closed?

When the load is connected to the supply, the current will flow through the load. And this condition is called a “close circuit.” In this situation, we can notice some changes in this electrical circuit.

  • When we connect a bulb as a load, the bulb will glow when the circuit is closed.
  • When we connect the motor as a load and close the circuit, the motor begins to move.
  • When a heater is connected to a circuit and the circuit is in good working order, the heater begins to emit heat.
  • As a result, when any type of load is connected to a closed circuit, the load begins to operate.

Types of close circuit:

There are some types of closed circuits, which are given below.

  1. Series circuit
  2. Parallel circuit
  3. Compound circuit

Now we will discuss each of the above types of closed circuits separately.

What is a series circuit?

In this type of circuit, many loads are to be connected in series order. As you can see in the image below, in this circuit, the first terminal of the supply source is connected to the first terminal of the first load. And the first load’s second terminal is connected to the second load’s first terminal, the second load’s second terminal is connected to the third load’s first terminal, and the second terminal of the third is connected to the supply negative terminal. And thus, this connection is called a secure circuit.

What is electrical circuit
series circuit

Properties of a series circuit:

There are some properties of series circuits. which is given below.

  1. There is only one way to flow current in a series circuit, which is through all the loads. As a result, the current in this connection will be the same. It means I = I1 = I2 = I3.
  2. Due to the series connection, the voltage drop level is different at every load terminal. That’s why every load has a different voltage level. So the total voltage value is V = V1 + V2 + V3.
  3. Ohm’s law states that voltage drop is equal to the product of current multiplication and load resistance.
  4. Due to connecting the load in series, the resistance of the load is also connected in series. So total resistance is equal to the sum of all loads’ resistance. R = r1 + r2 + r3.
  5. A closed circuit will become open when one of the loads is disconnected due to any fault. All loads will stop operating. It means that each load is dependent on the others.
  6. If all loads have the same rating and are connected in series, the supply voltage is divided equally at each load. However, if the load rating is not the same, the supply voltage will divide based on the load rating.
  7. If two loads with the same watt rating are connected in series, the total power of the circuit will be halved.

Application of a series circuit:

There are some applications of a series circuit, which are given below.

  1. As we know, in a series circuit, voltage is divided for every load. As a result, we can use a series of low-voltage loads, like a miniature bulb.
  2. The fuse is also connected in series order.
  3. To connect an overload coil, a series circuit or order is used.
  4. If we want to connect multipliers in a voltmeter, we have to connect multipliers in series order.
  5. If we want a high voltage level with a small cell, we have to connect many cells in series to increase the voltage rating.
  6. To measure current, an ammeter should be connected in series to the power supply.

What is a parallel circuit?

In this circuit, all loads will be connected in parallel. As you can see in the images, there are three types of resistance, each of which is connected to the power supply separately. All three resistances aren’t dependent on each other.

What is electrical circuit
parallel circuit

In a parallel circuit, current values are different at every load or resistance. And every load gets the same rating of voltage. Every load draws current according to its rating.

Properties of a parallel circuit:

  1. In the case of a parallel circuit, each load receives the same voltage supply.
  2. Suppose that our supply voltage is 250 volts and all loads are connected in parallel. All loads will get 250 volts. As a result, total voltage V = V1 + V2 + V3
  3. In a parallel circuit, the current value will be different at every load. If the load rating varies. So total current is the sum of all current-drawing loads. I = i1 + i2 + i3
  4. Total resistance, which is connected to total conductance, is universally proportional to total resistance.
  5. Total resistance will be decreased when we connect a greater number of resistances in parallel circuits.
  6. If different types of three-wire resistance are connected in parallel order, the total value of resistance is less than the lowest resistance value of the load.
  7. Only the faulty load will be affected if one of the loads fails due to any condition. The remaining load will still be operating.

Application of parallel circuits:

  1. We mostly use parallel circuits for things like house wiring, panel wiring, various types of motor wiring, and light and fan wiring.
  2. If we need to connect a lamp, we can simply do so in parallel.
  3. Voltmeters must also be connected in parallel.
  4. In the case of a shunt, the ammeter should be connected in parallel.
  5. If we want to increase current capacity by means of cells, we can connect various cells in parallel order.

What is a compound circuit?

A compound circuit is a mixture of a series circuit and a parallel circuit. This circuit is generally available in the electronic field.

What is an open circuit?

An open circuit is a condition of an electrical supply system. In this condition, a circuit is not completed. It means that no supply current will pass through the load. If we close a circuit and then turn off the switch, the circuit will reopen.

open circuit

Open circuit conditions can occur:

  • The circuit will be open if the switch is turned off.
  • If the fuse fails.
  • If there is a fault in the load,
  • If the circuit wire has been severed.

What is a short circuit?

Current will not flow through the load if the supply’s two wires (positive and negative) are touched. Current will pass through the shorted wire; this condition is called a short circuit of the supply system.

short circuit

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