Basic electrical : Current, Voltage, Power

by Editor - Jan-10-2026

Current, Voltage, and Power Current means flow. Whenever we operate an electrical device, a flow of electric charge takes place. But think about this: when we buy a torch cell (battery) from the shop, does it already have current inside it?
Of course not!

But it does have voltage. A typical torch cell has 1.5V. Current is produced only when we connect a torch bulb to the cell and the bulb lights up. That means the stored charge inside the cell starts flowing through the bulb. If we look at it as a whole, the charge flows from the cell, through the bulb, and back into the cell. (See Figure)

Current is measured in Amperes, and it is denoted by I. To understand it more clearly, watch our YouTube Video on below link.

What is Voltage?
We said that a torch cell has voltage even before we connect anything to it. Voltage is simply the force that can create current - the push that makes the charge flow. It is just like the water tank kept on top of a building.

You have learned about potential energy.
Voltage is a kind of potential energy. This energy exists inside a chemical-filled battery, at the ends of a coil moving inside a magnetic field in a dynamo, or between the terminals of a solar cell exposed to sunlight.
Voltage is measured in Volts.

What is Power?
Power is Voltage x Current. It is measured in watts (W).

For example, if 2A of current flows through the bulb shown in Figure, and the battery is 1.5V, then the bulb's power is:
Power = 2A x 1.5V = 3W
So it is a 3-watt bulb.

W = V x I