Think of electricity as flowing water. Electricity flows down a conductor in the form of billions of electrons. A conductor is any material that allows electricity to flow through, like a metal wire. When electricity flows, we call that an electric current.
Just like the rate at which water flows is important, the rate at which electricity flows is also important. Electric current is measured in Amperes, which can be shortened to Amps or even the letter A. For example, a current of 2 Amps may be written as 2A. When an electric current gets bigger, it means more electricity is flowing.
Now that you know electric current is measured in Amperes, it’s time to learn where that electric current comes from. Just like water flows from high elevations to low elevations, electric current is created by the potential difference in an electric circuit.
This potential difference is created by a device like a battery, which forces electricity to leave through one end before cycling through the circuit to arrive at the other end. This is considered a complete circuit, and different batteries cause different amounts of pressure throughout an electric circuit.
Think of the battery like a water pump. Water is propelled through the pump just as electricity is propelled through the battery.
The potential difference (pressure) provided by a battery is measured in terms of Voltage, also known as Volts or simply V. A Voltage of 3 Volts would be written as 3V.
As voltage increases, more pressure is created throughout the circuit, causing more current to flow. But electricity will only flow if the electrical conductor (i.e. the wire) loops back to the battery to form a complete circuit. If that circuit is broken (say, by a switch) then electricity will not flow and we get what is called a short circuit.
So far, the electrical circuit we’ve built hasn’t done much of anything. It’s a battery connected to a wire that loops back on itself. The only thing that circuit will do is cause the battery to drain itself. And since there is very little resistance in the circuit (the only resistance is provided by the conductor), a huge amount of electric current would continue to flow until the battery was empty.
To take advantage of this electrical current, we need to understand Resistance. Resistance is something that slows the electric current down. A light bulb attached to the circuit, for example, would slow the electric current down while illuminating a room.
When we attach a light bulb to the circuit, that light bulb adds plenty of resistance. To go back to the water analogy, a light bulb effectively narrows the pipe through which water flows, making it more difficult for a large amount of water to flow through.
The light bulb reduces the current flowing in the circuit, causing the energy in the battery to be released more slowly. The stored energy from the battery is now being transformed into heat energy and light energy through the light bulb.
Resistance is measured in terms of Ohms, also written as the Greek letter Ω (Omega). A resistance rating of 5 Ohms could be written as 5Ω.
Those are the basic concepts of electricity. Potential difference (measured in volts) causes electric current (measured in amperes) to flow through a circuit, where it encounters resistance (measured by ohms). In the next post, we’ll explain how these three concepts are mathematically related to one another through one simple formula.