Eli5 how does playing around with different metrics of amps, ohms, and volts alter how powerful electricity is?


Eli5 how does playing around with different metrics of amps, ohms, and volts alter how powerful electricity is?

In: 9

Think of electricity like water through a hose. The current (amps) is the amount of water you are putting through the hose. The voltage is how hard you need to push to get that amount of water through the hose. The resistance (ohms) could be the size of the hose pipe you use.

Current, voltage, and resistence are related by the simple equation V = I x R, voltage equals current multiplied by resistance. This means we can work out what happens when we change these numbers.

Back to the water hose. If you increase the current (amount of water flowing) but keep the size of the hose pipe the same, what happens? You need to push a harder to get more water through the same size pipe (I.e. voltage increases).

What if you keep the voltage the same but make the hose pipe thinner? The thinner pipe increases resistance, so you get less current through the pipe!

It doesn’t, at least not necessarily. The power delivered is not measured in volts or amps, it is measured in watts. The amp (actually ampere) is a measure of current, while the volt is a measure of potential.

If you have a device that consumes 1200 watts and can work with any voltage if you were to supply it at 120 volts it would require 10 amps of current. At 12 volts it would require 100 amps. At 1200 volts it would require only 1 amp.

The ohm is a measure of resistance to the flow of current. When current flows through a resistance power is dissipated as heat. All wires (leaving aside superconductors) have some amount of resistance, so higher current means more wasted power. This is why transmission lines use a much higher voltage than is used in your home. The same power can be transmitted with a lower current, so less is lost to heat.

Resistance also affects how much current can flow at a given voltage. Other answers have already covered the details, so I won’t repeat it here.

There’s two main equations for electrical power.

P = I*V, or (Power in Watts) = (Current in Amperes) * (Voltage in Volts)

and V=I*R, or (Voltage in Volts) = (Current in Amps) * (Resistance in Ohms)


So if you have a basic circuit, the resistance is roughly constant during normal use. And voltage and current are directly dependent on resistance. So lets say you have 9 Volt battery, and you hook it up to a 100 Ohm circuit. V=I*R, you can calculate that the current will be 9V/100Ohm, or .09A or 90mA (milliAmperes). With P= I*V, we get 0.81W.

To get more power, we can increase the voltage, which will increase the current as well. Or we can reduce the resistance, which will increase the current while the voltage stays the same.