Resistors: Adjusting the Voltage to Fit

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Resistors do the work of regulating the flow of electricity around the circuit. Electricity seeks the path of least resistance: the higher the rating of the resistor, the less electricity that will flow across it.

Also, resistors "use" voltage, according to their "rating" and thus can change the available voltage to fit the other components in the circuit.

Resistors come in a variety of wattages: for this project, you may use either 1/4 watt or 1/2 watt resistors.

Ohmmmmmmmm....
It's all about Ohms...

You can put the resistors in with either end facing either way: it doesn't matter.

This is NOT true of diodes, which must be inserted in the correct "direction" to regulate the flow of electricity.

Fortunately, resistors are relatively inexpensive and readily available. Radio Shack has them for about 20 cents each or you can order them in bulk from online sources for about a nickel each.

Be careful to get the right size resistor: it is easy to confuse 10 ohm with 10k ohm or 2.2k ohm with 2.2 ohm. You can tell what size the resistor is by the colored bands on them. You read the colors from left to right: the end with the gold band goes on the right. Each band gets a different numerical value...then you do some *really fun* math to come up with the ohm rating of the resistor.

Or, if you are adverse to squinting at bitty little electronic parts, it might be easier to keep the resistors in their package and just read the label. Doh!

But if they get dumped out on the table, this web site might come in handy. Here is a calculator that does the math for you:
http://webhome.idirect.com/~jadams/electronics/resist_calc.htm

Test Question:
What ohm rating is the resistor used for the top of Resistor Man's head in the photo at the top right of this web page?

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