Electricity – basics like voltage & current, some dude named Ohm
I bet you just love me hopping around from topic to topic don’t you? Especially when it comes to our training. So far we have done pumps, some engineering fundamentals, and some building engineering fundamentals like systems you can expect to see.
We are going to sort of continue down the basics of engineering path and today define some simple electrical stuff – terms like voltage, current, and resistance. And then we will briefly get into this crazy cat named Ohm who so lovingly gave us Ohm’s Law. Why can’t I have a law named after me? Larsen’s Law. It says the same thing as Ohm’s Law just in a cooler way.
Basic Electricity – let’s define some terms yo
Out of all of the systems around – let’s just say there are 3 main categories (mechanical, electrical, & electronics) – I had the hardest time understanding and grasping electricity. I still do as a matter of fact. I didn’t have much exposure to electrical stuff before the Navy other than wiring up car stereos, speakers, and amps way back. It confuses me. I am getting better though.
What is electricity?
Electricity is a combination of a force, known as voltage, and the movement of particles that we can’t see, known as current.
The force of voltage can be compared to the force generated by a pump, which I wrote about in an earlier post. Voltage is the force that causes current to flow through a system of wires, or a circuit. Current is the movement of invisible particles that causes electrical devices to function.
Current consists of electrons, which we talked about earlier in this post. And again, voltage is the force that causes current to move through wires and our precious electrical devices.
We cannot see current, but we can determine its presence by the effects it produces. A motor rotating, an illuminated light are two examples we can use to verify that current is flowing.
Resistance is the amount of opposition to the flow of current.
Hold up a second
Twice now I have compared the flow of electricity to the flow of water. There is one huge difference though – water can continue to flow out of a busted pipe. Current cannot flow out of a broken wire or conductor. When a wire is broken, the force of the voltage is removed.
My main man Ohm & his law
Some time in the 19th century, a guy named Georg Ohm conducted an experiment and proved that a precise, definable relationship exists between current, voltage, and resistance. This relationship is called Ohm’s law.
Current is inversely proportional to resistance. This means as the resistance in a circuit increases, the current decreases proportionately.
Apparently the equation for this is I = E/R – where:
- I = current
- E = voltage
- R = resistance
I learned this as V = IR, or voltage is equal to current multiplied by resistance. It doesn’t matter though – if you know 2 of the variables, you can figure out the 3rd so solve the equation for that. Have you ever seen the little handy electrical circle that makes this pretty easy to remember? I’ll look for it and try to add it as an image.
Really, really basic stuff today. We covered some basic electrical terms – voltage, current, and resistance. We also defined Ohm’s Law which says that current is inversely porportional to resistance. Remember, voltage is the force behind the current, resistance is the opposition to this flow of current.