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Electrical/Electronics Basics

This is where a lot of people's eyes go foggy; and they instinctively tell themselves they don't understand. Hopefully, I can explain it in a way thats a bit easier to grasp. It's my theory that electricity becomes difficult to grasp because you can't see it. I like to explain it in terms of something you can see - water!

Lets start out with a regular old garden hose. You know there is water pressure in it; you know water flows out of it; and you know what happens when it gets a kink in it. So, thats about all you need to know to understand basic electricity - really!

The water pressure represents something called voltage; how fast the water is flowing represents amperage, and the kink represents resistance. It really is that simple; its just that with electricity we often have lots of hoses (wires), and lots of kinks (resistors).

Now, who said water and electricity don't mix?! Seriously, reread the above so that you have a very good grasp on those three building blocks - they are the three fundamental concepts on which all electrical/electronics theory is built; and you will be very suprised how many circuits you can figure out and/or explain by thinking of the electricity as water inside the wire.

Ohms Law

So, here comes the mathematical part. Obviously, we need to be able to predict whats going to happen in a given electrical circuit. To do that, we use something known as Ohm's law. It's a very simple formula based on the above three building blocks: Lets go back to the water to start with..

Pressure = Flow times Kinks

What this tells us is that the amount of pressure we need to fill the bucket in a certain amount of time depends on how many kinks we have. Sounds logical, right?

Now, lets say that again in terms of electricity:

Volts = Amperage times Resistance

which is commonly written as

V = I • R

The explanation of this formula is just as it was for water - the voltage(pressure) required to flow the electricity thru the wire will be equal to how fast we need to move the electricity(water) multiplied by the number of resistors(kinks) in our wire(hose).

One thing that might trip you up here .. The letter "I" is used to represent current which is measured in amps. Where did they come up with an "I" from the word amperage?! There is a legitimate explanation for that somewhere; but for now lets just assume the engineers didn't want us to understand the formula - it helps them seam magical!


There is one more subject, and of course a couple of formulas, that should be covered in this section. Don't worry, as I promised above, it will build on the three fundamentals blocks above. However, it could be said that its importance almost makes its a fourth building block; and in fact its name is even commonly used when referring to an electrical supply.

The additional block is called power. It is measured in watts; and you will commonly find it stated with everything from milli(1000 of a watt) to mega(1,000,000) prefixes depending on the subject at hand.

If you look up the definition of the word, you will find that it means the ability to do something. To continue with our water analogy, you might relate it to the ability to fill the bucket. The more pressure on your hose, the faster the bucket will fill up; and if the water is coming out of the hose faster it will fill the bucket faster as well.

Again, it is no different with electricity. More voltage(pressure) or more amperage(flow) will provide more power.

Lets see how that all works out mathematically now. There is actually two commonly used formulas to determine power; and the one we use just depends on what we already know or can measure easiest. They are:

Power in watts = Voltage in volts multiplied by Current in Amps
P = V • I or P = I2 • R

They are really the same formula; the second one is arrived at by simply replacing V with IR; which we know are equal from Ohm's law above. Its just easier to know both forms; so we don't have to stop and figure out the substitution.

The end result, the formula tells us we can get more work done from a given source of electricity if we increase either the current or increase the voltage (or both of course).

Okay, that was all a little long; but I hope it was helpful. In the next section, we can start discussing a few common parts and components. Don't worry, we'll bring our water bucket and garden hose right along there too!

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