As an Electrical Engineer (power systems) I enjoy the subject of electricity and power more than most. Unfortunately when I get excited on a topic, I forget that many people don’t have the knowledge background I do. Even fundamental things like voltage and current dont fall in your normal persons vocabulary. I think the topic feels to difficult to most, when in actuality it is not too bad. My freshman year in engineering school a professor explained Electricity’s basic units and theory using a water analogy. I share my version of that now. Hope it helps you as much as it did me.
Voltage: We see this used all over the place. On batteries, in our homes, and on really any modern device. The analogy here is to water pressure. Think a spigot on a house, or a water pump.
Current: Again this is a common quantity. You see amp ratings on just about all electric devices. Amp or Ampere is the unit for current. The analogy here is to water flow, or more specific the amount of water flowing through a cross sectional area per unit time. Think of how fast and how much water is flowing out of your hose.
Resistance: If you have ever heard of the term Ohm, that is resistance. As the name implies it resists the flow of electricity. It is a physical characteristic of a metal or other material. The analogy here would be the hose. Obstructions or anything restricting flow in the hose would increase its resistance. A kink in the hose may also work here.
Let’s put it all together. Think of your hose outside. You can turn on the water and get a certain pressure out of the end of the hose. Your spigot is like an adjustable voltage source. Given the same hose, I can increase the flow (or current) from the hose by increasing the water pressure (voltage). Now if a change the hose to one with dirt in it, or put a kink in it, using the same water pressure (voltage) the flow (or current) will be less. Do you see all the quantities are linked? The basic math for this linkage is:
Voltage = Current x Resistance.
How is this remotely useful? Normally you won’t need to understand any of this on a daily basis. If however you are buying something with various voltage ratings or current rating, it’s good not to totally be in the dark. While I doubt this analogy is life changing, hopefully it helps you visualize these concepts a bit better. If nothing else it gave me a chance to nerd out.