Posted In: Physics

An electric circuit is a pathway through which electrons flow from a voltage source. The point where the electrons enter the circuit is called the ‘source’ and the point where the electrons flow out of the electrical circuit is called the ‘return’ or ‘earth ground’.  

There are two requirements for an electrical circuit. The first is a conductive path from the positive terminal to the negative terminal. A closed conducting loop is not a circuit until it extends from the positive terminal to the negative terminal of the electrochemical cell. There has to be a closed conductive loop from the positive terminal to the negative terminal in order to make a circuit and for the current to flow.

The second requirement is that there must be an electrical potential difference across the two ends of a circuit. There should be a source of energy capable of increasing the electric potential energy of a charge for it to move from lower energy terminal to higher energy terminal. These two requirements are  a must in order to make an electrical circuit.

Did you know: Electricity travels at the speed of light -- that is at a speed more than 186,000 miles per second?

When there are  two and more components in a circuit they can be connected in two ways. As a result there are two types of electrical circuits:

Series circuit

Series Circuit | Image source:

In a series circuit, the components are connected in a manner that there is a single path for charge flow.  In the series circuit the current through each component is the same and the voltage is the sum of the voltages across all the components of the circuit. If one of the component stops working the other components will also not work. Thus in a series circuit for all the components to work in a circuit each component has to work.

Parallel circuit

Parallel Circuit | Image source:

If a parallel circuit the components of the circuit are connected in parallel. In parallel circuit the components have the same voltage across their ends. If one of the component stops working then the other components continue to work as there is current in the other branches. Thus in a parallel circuit, even if one of the components does not work the others continue to work.

How to make an electrical circuit?
An electrical circuit is a closed path in which the electrons flow. You can make a simple electric circuit with a battery, light bulb and wires. In order to connect the circuit:

  • First connect two wires at the two ends of the battery.
  • Fasten the other end of the wire to the light bulb.

Connect the other point in the light bulb to the other wire connected to the battery.

The wires will conduct electricity from the battery to the light bulb. This simple circuit is ready. In the circuit the electrons will flow from the battery through the wires into the light bulb. The light bulb will light when connected to battery.

In the above circuit there are two parts viz internal circuit and external circuit. The part of the circuit containing the electrochemical cells of the battery is called the internal circuit. The part of the circuit where charge is moving outside the battery through the wires and the light bulb is called the external circuit.


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