Hey friends! Ever wondered, what drives the current in an electrical circuit? What’s the role of a battery we get at the electrical stores. For those of you, who are really fascinated by gadgets, electrical appliances, in this video we find out that do we really need a battery in a circuit. Let’s have a look at this with the help of an example. Consider I have a pipe connected to a tank. If I keep this pipe horizontal, from my intuition, I know that water will not flow out of this pipe. But, if I tilt the pipe a little, water starts to flow of the pipe. And as I keep on increasing the angle of the tilt, the flow of water also starts to increase. This is because of the pressure difference between two ends of the pipe. The force of gravity is responsible for this pressure difference. The force of gravity creates a potential for the flow of water. But in case of electrons, gravity doesn’t have any role to play. The electrons move only when there’s an electric pressure or potential difference between two ends of a conducting wire. Ok, let’s connect a battery to a circuit and see what happens. The potential difference provided by a battery sets the charges in motion, which is similar to the flow of water in a pipe, as we saw in our example. The work which gravity did for the flow of water in a pipe is done by a battery here. The battery provides the necessary potential difference, which is responsible for the flow of current in a circuit. So, how do we define potential difference mathematically? Potential difference in a current carrying conductor is defined as the amount of work done to move a unit charge from one point to the other. I repeat, it is the work done to move a unit charge from one point to the other. Potential difference is represented by V which is equal to work done in joules divided by the charge in coulombs. So, 1 Volt is the potential difference when 1 Joule of work is done to move a charge of 1 Coulomb from one point to the other in a current-carrying conductor. Therefore, 1 Volt is equal to 1 Joule per Coulomb. The SI unit of potential is Volt. The instrument used to measure potential difference is a Voltmeter. To measure the voltage across any two terminals, we connect the Voltmeter across those two terminals. The reading shown by the Voltmeter gives us the value of the voltage.