# Blog - Ohm's Law -- Practical Application

Anyone who’s been around this net for any amount of time and knows me well knows one thing. I have a math phobia that goes back to the day when I had to sit down and explain to my engineer father how I “reinvented” subtraction because the way the teacher taught me was too hard. So little artistic me, I invented another way to subtract. And of course, I missed EVERY question on the test.

Aside from that, though, I’m pretty technical minded. I love to figure out the how and why things work out UNTIL the math comes in. I don’t mind numbers, but anything with a formula? Yick. As it turns out, ham radio has quite a few formulas. I usually ignore them, but every now and then I find a practical application for a formula and then all bets are off. I'll learn it because I NEED TO KNOW IT.

Ohm's Law is one of those "need to know" formulas.

So, in an attempt to educate myself, I decided to learn and understand it. Be one with it. Grasp it. (Deep Breath!) Teach it. (Closing eyes.) Okay, cover me. We're going in. Ohm's Law and WHY you need to know it.

A few reminders of basic definitions.

Electricity, or current, (i) is the flow of electrons through something, such as a wire or circuit and its measured in amps (a).

Voltage (e) is the electromotive force behind that electron that makes it move and it's measured in volts (v).

Power (p) is the rate at which electricity is used and it’s measured in watts (w).

Enter Ohms' Law

Power (p) = Current (i) x Voltage (e)

Or PIE for short. I love pie. Cherry pie, lemon meringue, fried apricot pies, key lime pie! To quote my brother… Pie… is good. And when you’re talking about Ohm's Law….Pie is also pretty wonderful, but it doesn’t hold the same attraction as lemon meringue for me. But I digress. Back to pie. Mmmmm. Pie.

Understanding the inter-relations of voltage and current is the key to making Ohms’ Law relevant to you and your hamdom.

A good analogy as to how current and voltage interact is a water pipe. Voltage acts like the pressure in a water pipe and current acts like the water. You can have pressure behind the water but no flow if the tap is turned off. You can have pressure and flow if the tap is turned on. But you can’t have flow without pressure. Essentially then, you must always have voltage or you will have no POWER because there will be no electrons moving.

Back to power. Power (p) – is the rate at which electricity is used and it’s measured in watts (w). If you think about it, this makes perfect sense since the amount of force behind the electrons will be the deciding factor in how many electrons are moved down the pipe at a given time.

It might make this whole thing a little less confusing if there weren’t two different formulas that mean the same thing.

There’s the big picture, PIE, Power (p) = voltage (i) x current (e)

But what we’re actually dealing with here are the units of measure and not the big picture. Power (p) is measured in watts (w). Current (c) is measured amps (a). Voltage (i) is measured in volts (v). So PIE has now become WAV. It’s a happy convenience that they both have a vowel in them so you can remember.

Memory trick!!!

“Who would like some PIE?”

Let’s talk math again. Refer to the picture posted with this blog -- the WAV circle.
If you have two of the these units -- watts and volts, volt and amps, etc, you can solve for the missing element using this circle. Just place your finger over the unknown quantity. The circle will tell you what function to perform. (Divide or multiply.) If what’s NOT covered is on the top and bottom, divide the top by the bottom. If what’s not covered is side by side, multiply the two numbers.

Okay, let’s go. Practical application.