Powering Your Breadboard:

We'll call the row of holes along the red line the power rail, and we'll call the row of holes along the blue line the ground rail.

Testing With The Multimeter:

And Now, Your First Circuit: A Safely Illuminated LED

Safety warning! There are potential safety issues any time you wire up an analog circuit. In the upcoming lessons on Ohm’s Law and power, I’ll give a clear mathematical explanation of what can cause components in your circuits to overheat, damage themselves, or even explode. Until then, I’d recommend you only build the exact circuits I do, using the exact component values I do, for your own safety.

An LED is a polarized component, meaning it only works if you plug it in the right way.

Resistors are not polarized, so they will work exactly the same regardless of which way you plug them in.

The resistor controls how much current flows into the LED. More resistance means the less current flows, and vice versa.

The math of how you determine the right resistor will be shown later. But the general idea is that if too little current, or no current, flows though the LED, it doesn't light up. If too much current flows through the LED, it overheats and permanently destroys the LED. If a current flows through the LED that's not too little, and not too much, it safely lights it up. Within that range of current that can safely illuminate it, you can safely adjust the brightness, as we will shortly.

Here's a quick sidenote on the metal plate which came with the breadboard, which may or may not be attached to yours.

If your metal plate isn't attached, you don't have to pull everything off your breadboard and attach it right this moment, but you should some time soon. I'd suggest the next time you take everything off your breadboard.