RESISTANCE
Maybe a little out of order, but we definitely need to talk about “resistance”. Thus far we have discussed voltage, or pressure in and electrical system, current, or flow, and the concept of a circuit. As we discussed, the voltage, or pressure causes the movement or flow of electrons in a loop, or circuit. As the electrons flow around the circuit, they encounter opposition or more correctly, “resistance” to their continued movement through the circuit.
ANY opposition to the flow of electrons in a circuit is known as resistance and can be quantified by a value known as OHMS, a value of resistance. Generally speaking, everything and anything that electrons flow through has a resistance. Some things have a very low resistance value, such as copper wire, while other things have a very high resistance value such as the insulation used to cover wire.
If you consider resistance in a circuit, you will soon realize that any resistance will cause the flow of electrons to “slow down”, or reduce. This is correct. The amount of slowing down can be easily calculated.
Please don’t get frightened by the reference to math. Math is an essential part of electricity and a basic understanding of some of the math formulas used in understanding electrical circuits really helps. We will save our math discussion for a future post. For now, we need to know that given a specific value of voltage in a circuit, and with a known value of resistance in that circuit, we can easily determine how much current will flow in that circuit.
This ability is important for many reasons, but one reason that is important when trying to troubleshoot or repair electrical systems in an RV is related to one of my troubleshooting icons:
IF YOU ARE MAKING AN ELECTRICAL TEST IN A CIRCUIT, BEFORE YOU MAKE THE TEST, HAVE AT LEAST SOME IDEA WHAT YOU EXPECT TO MEASURE, BEFORE YOU MAKE THE MEASUREMENT!!
Ok, sorry, didn’t mean to shout. But there are some things I feel very strongly about and my troubleshooting icons relate those concepts.
Anyway, when we discuss how to calculate current flow, we will do so because we can use that information to troubleshoot and repair electrical systems. Really!!! We can do that!!