Elenco Basic Electronic Experiments - Manual (Page 5)

The Resistor: Why is the water pipe that goes to your kitchen faucet smaller than the one that comes to your house from
the water company? And why is it much smaller than the main water line that supplies water to your entire town? Because
you don’t need so much water. The pipe size limits the water flow to what you actually need. Electricity works in a similar
manner, except that wires have so little resistance that they would have to be very, very thin to limit the flow of electricity.
They would be hard to handle and break easily. But the water flow through a large pipe could also be limited by filling a
section of the pipe with rocks (a thin screen would keep the rocks from falling over), which would slow the flow of water but
not stop it. Resistors are like rocks for electricity, they control how much electric current flows. The resistance, expressed
in ohms (
Ω, named after George Ohm), kilohms (kΩ, 1,000 ohms), or megohms (MΩ, 1,000,000 ohms) is a measure of
how much a resistor resists the flow of electricity. To increase the water flow through a pipe you can increase the water
pressure or use less rocks. To increase the electric current in a circuit you can increase the voltage or use a lower value
resistor (this will be demonstrated in a moment). The symbol for the resistor is shown on the right.
Your Breadboard: Breadboards are used for mounting electronic components and to make connecting them together
easy, and are similar to the printed circuits boards used in most electronic devices. Breadboards make it easy to add and
remove components. Your breadboard has 830 holes arranged into rows and columns (some models may have more or
less holes but will be arranged the same way):
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Symbol for RESISTOR RESISTOR ROCKS IN THE PIPE
BREADBOARD
“LEADS” for connecting