A deep insight to demystify voltage dividers with plenty of demonstrations and uses. We cover everything you are going to need here, if you just need to learn for an exam, or if you want to understand how to use these incredibly useful voltage dividers in your projects.

For anyone wanting to know how these equations are derived, search for Ohms law.

V=IR where V (sometimes written as E) is voltage, I is current in amps, and R is resistance in ohms.

The way I learned it when I was young was via the “water pressure, pipe size, flow rate analogy”, where V is like pressure (or the height of a water tower), I is current flow rate (water volume/unit time, e.g. liters/sec), and R is resistance (smaller pipes have higher resistance to flow). So to get the same amount of gallons per minute, through a smaller pipe requires higher pressure.

For wires made of the same conductor, a larger wire will have less resistance, and be able to carry the same current with less voltage drop. This is why longer extension cords usually are made of lower gauge (thicker) wire, so there will be less voltage drop when a load is applied to the far end of the wire.

It is also the reason high voltage is use to transmit electricity over long distances, because a lower percentage of the power will be lost to heat in the transmission lines. Watts (power) is VI (and V can be rewritten as IR), so power is II*R. By increasing the voltage, you can decrease the current needed to transmit the same power, and therefore get less power loss to heat in the transmission wires, and a higher percentage of the power delivered to the destination to do useful work. For example 10,000Volts * 0.01 Amps is 100 Watts, but uses 1/100 the AMPs that 100 Volts would require (1 A) to get the same 100 Watts power.