Table of Contents
Like Water, Electricity Flows from High to Low
- You’ve seen with streams of water on rainy day that water flows high ground to lower ground.
- Like water, electricity flow from high (+ volts) to low (ground / 0 volts).
A Wire is a Channel for Electricity
- While playing with streams you’ve probably dug channels so the water can flow through faster and where you want. Wires and metal are like that for electricity.
Air is to Electricity as a Dam is to Water
- If you’ve built dams across streams of water on a rainy day, you’ve probably built dams across them. With electricity air is like putting a rock much larger than the stream across the stream. Electricity can’t get through unless there is a really massive amount of it (that’s when you get lightning).
Consequences / Results / What This Means for Us
To allow electricity to flow from high to low you need a wire to create a channel the electricity can go through.
You don’t want to connect a wire directly from high to low because that creates an effect like a really big waterfall such as Niagra Falls — you end up with a huge amount of flow (current) which has too much power all once.
By itself an LED is basically a single direction wire that happens to light up when electricity flows through it.
So we add a partial dam, called a resistor, so that there is not too much electricity at once.
A button is basically a device that is a wire that can be removed from the path. When the button is pressed the wire is in the path. When the button is not pressed (open) the wire is not in the path, so the electricity is stopped by the air (dam).
Next we’ll see how to use this to understand the breadboards we’ve been using.