Difference between Open Circuit and Closed Circuit

Every device we use has a unique circuit. It contains circuit components and proper biasing for its operation. Do you think that just these things are enough to deal with a circuit? No way. You have to take care of some other conditions. To operate, a circuit needs electric current through it. You are probably thinking that it is very simple – if we switch it on, the circuit will get current and if the switch is off, the circuit will be OFF. This is true from another point of view. But what if the switch is ON, but there is no current flow through the circuit? This is where the concept of open circuit and closed circuit comes from.

In this post, I will try to explain the difference between an open circuit and a closed circuit. I’ll start with the basic things of a circuit and then will summarize the differences in tabular form.

Contents in this article:

  • What is Open circuit?
  • Example of Open circuit
  • What is Closed circuit?
  • Example of Closed circuit
  • Differences between Open circuit and Closed circuit.

What is Open Circuit?

If a circuit does not carry any electric current through it due to the broken connection, then the circuit will be called an open circuit.

A circuit will carry electric current only if its initial and final points are connected via some circuit elements and a power source. If we place a key or switch in the circuit and open it, the circuit will become an open circuit. Even, if you cut the wire of the circuit, the circuit will become an open circuit.

The open circuit condition is like the OFF stage of the circuit, but the switch of the power supply is not necessarily off.

Example of Open Circuit

We consider an electric circuit that contains a battery, resistance, and switch and a bulb as a load. Here, V is the voltage of the Battery, R is the resistance, B is the Bulb, S is the switch and I is the current through the circuit. The bulb will indicate whether there is a current flow or not.

Do you know why is the resistance used here? Tell me in the comment section.

Example of Open Circuit diagram
Open Circuit diagram

When the switch is opened, the bulb will not glow. That means there is no current flow through the circuit I = 0. So, the electric circuit with an open switch is an open circuit.

Does a circuit always need opened switch to be an open circuit? No, it’s not. If we remove the switch and close the circuit with an insulator, the circuit still behaves like an open circuit. Because the insulator will not allow the current flow.

What is Closed Circuit?

A Closed circuit is a closed loop that contains circuit elements and power supply and carries electric current through each component of the circuit.

The circuit should not be disconnected anywhere. If there is a switch in the circuit, it should be a closed switch.

A closed circuit requires the followings –

  • conducting wires
  • an active power source device (like a battery)
  • a complete path for flowing of electric current.

Example of Closed Circuit

Example of Closed Circuit diagram
Closed Circuit diagram

If the switch is closed, the bulb will glow. This indicates that the circuit is ON and an electric current is flowing through the circuit. At this condition, the circuit is a closed circuit.

So, an open circuit can be converted into a closed circuit just by closing all switches in the circuit.

Closed Circuit vs Open Circuit

I hope, the basic concepts of closed and open circuits have been cleared. Now, let’s write the differences between open circuits and close circuits in tabular form.

Serial
No.
Open Circuit Closed Circuit
1An open circuit doesn’t have a complete path for the current flow.A closed circuit contains a complete path for the flow of electric current.
2In an electrical open circuit, the active energy doesn’t flow from the source to the load.In an electric closed circuit, the active energy flows from the source to the load.
3An open circuit has infinite equivalent resistance.A closed circuit has a finite equivalent resistance which allows current flow.
4A circuit is opened to make it inactive i.e. an opened circuit indicates the OFF state of the circuit.A circuit is made closed to activate it i.e. a closed circuit indicates the ON state of the circuit.
Difference between open circuit and closed circuit

Conclusions

An open circuit means that there is a disconnection in a circuit and thereby no current flows through it even after applying power sources. A closed circuit has a complete loop for current flow. To use any circuit, we need to provide electric current to it. That means an electronic or electric device has a closed circuit in it.

This is all from this article on the difference between open circuit and closed circuit. If you still have any doubt on this topic you can ask me in the comment section.

Thank you!

Read also:

  1. Circuit Elements and their uses
  2. Different Types of Electric circuits