Lesson 1: Basics of Electricity

The purpose of this lesson is to learn the basics about electricity. We are going to go over how some basic electrical components work and what they do. We are then going to use those components to turns on a light, as shown below.

 turn on a light

The first lesson is about electricity because computers are not only powered by electricity, but also use electricity for everything that they do. Without electricity, your computer wouldn't work, and there would be no way to interact with it. For example, keyboards use electricity to tell a computer what keys you press. Speakers use electricity to make sound. Light bulbs use electricity to make light. And this course is going to teach you how to use electricity to build a game of laser tag. 

The first thing we are going to nee is a source of electricity, which, in our case, will be a battery. A battery stores electricity so you can use it later. However, electricity won't just fly out of a battery and into something. Electricity likes to move through certain materials. In particular, it likes to move through metal. When we want electricity to flow through something, we need to build a path out of metal for the electricity to move through. This path is called a circuit.

The battery we are going to use is a nine volt battery, pictured below. A nine volt battery has two chemicals in it. Each chemical is attached to pieces of metal on the outside of the battery. Electricity can flow from the chemicals in the battery to a circuit outside of the battery. One of the chemicals, on the plus side of the battery, has more electricity in it than the chemicals on the minus side. The plus, or positive side of the battery, has a + sign and an arrow pointing to the piece of metal, called a terminal, that is connected to the chemicals with more electricity. Electricity will only flow from the positive side, with the plus sign, to the negative side, the one without the plus sign. 

9 V Battery

So, how much electricity do you get out of a nine volt battery. There are two factors to that. How much electricity is in the battery, and how hard the electricity is getting pushed out of the battery. Nine volt batteries don't have a lot of electricity inside them. But, compared to a AA battery, they push electricity a lot harder. How hard the electricity is pushed out of  the battery is called Voltage. It's called Voltage after Alessandro Volta, who made the first battery. And, if you invent something, you can name it after yourself too so that countless generations will have to learn your name. 

The next thing we need to add is something made of metal that the electricity can flow through. We are going to use a metal wire that has clips on the end. Electricity can flow through the clip, into the wire, and out the other clip. The clips and the wire are covered in different colored plastic. Electricity doesn't like flowing through plastic. We will use plastic coated wires a lot, and the plastic keeps the electricity from going where we don't want it to go, like into the ground or across your desk.

wire with clips

We then clip one end to the plus side of the battery. 

The next thing we are going to add is a light bulb. The light bulb we are going to use is called an light emitting diode, or LED for short. LED's come in many sizes and colors, and they do not use very much electricity to make light. You've probably heard of LED light bulbs in houses or other electronics. These are the same thing. LED's have a unique quirk that electricity only likes to flow through them in one direction. If you try to have electricity flow through the LED in the wrong direction, it won't work. The LED's that we are going to use have two wires coming out of it, which are sometimes called legs. One of the legs is longer than the other one. Electricity can only go in through the long leg and out through the short leg.


To make it easier to connect, we are going to bend the long leg so that it is going to the right, as shown below. 

LED long leg bent

Then connect the long leg to the other end of the wire connected to the plus end of the battery. That creates a path out of metal for the electricity to flow through. 

with LED

 So you might be thinking that all we need to do is add another clip going from the LED to the other side of the battery (named the minus side). Then we have a path for electricity to flow out of the plus side of the battery, into the LED, and then back to the minus side of the battery. Unfortunately, it's not that simple. A nine volt battery pushes too much electricity for the LED. Since we can't change how much electricity gets pushed out through the battery, we will need to add something that will prevent too much electricity from flowing. To do that, we need a resistor. 

A resistor is an electrical component that tries to keep electricity from flowing through it. We measure how hard it is for electricity to flow through a resistor, or the resistance, in Ohms (named after Georg Ohm, another guy who discovered something and named it after himself). The more resistance a component has, the harder it is for electricity to flow through it.

Three different resistors are shown below. They had different colored bands on them that designate how much resistance they have. Most of the colored bands are the same. There is only one band that is different, and that color is either brown, red, or orange (from left to right in the picture below. It's hard to see that the bands on the LED's are different colors, but trust me, they are).


From left to right, the resistor with the brown stripe has the smallest resistance, the one with the red stripe has a middle amount, and the one on the right with the orange stripe has the most resistance. If we let too much electricity through the LED, it could break, so we don't want to let too much electricity go through the resistor back to the battery.

One way to think about this problem is to use an analogy for electricity flowing through a wire as air blown through a straw. If you blow into a straw as hard as you can (like the nine volt battery pushing electricity as hard as it can), the size of the straw will determine how much air goes through. Similarly, the size of the resistor determines the amount of electricity that goes through. If you have three straws, like the ones below, blow through them and try to match up the straw with the resistor. There is a thin coffee straw, a regular bendy straw, and a wide boba straw. 


Ready for the answer?

The straws are lined up next to the resistor they represent. The one with the lowest resistance is on the left, and the highest resistance is on the right.

Straws and Resistors

It is easy to blow through air through the wide boba straw, and a lot of air comes out. That straw has the least resistance and will let the most air through. This straw is like the resistor with the brown band, which has the least resistance and will let the most electricity go through it. The middle straw is in between, which is like the resistor with the red band. It has a middle amount of resistance and will let some electricity through. Finally, it is hard to blow air through the thin coffee straw, and not a lot of air comes out. That straw has the most resistance, and matches with the resistor with the orange band. That resistor also has the most resistance and will let the least electricity through. 

If we use the brown resistor, too much electricity can be pushed through than our LED will like, so we don't want to use that one. If we use the orange resistor, not very much electricity will be pushed through, so the LED won't be very bright. We want to use the resistor with the red band so that some but not too much, electricity flows through it. 

We then use another wire with clips to connect the shorter leg of the LED to one side of the resistor. Resistors aren't as fussy as LED's. Electricity can flow through the metal legs sticking out of them on either side. It doesn't matter which way you connect it. It only matters that you connect the clip to the metal sticking out of the bumpy thing with the bands on it. You can't connect the clips to the bumpy thing with the bands. 

Adding Resistor

Now all we need is one more wire to give the electricity a path from the plus side of the battery to the minus site. The electricity goes through the red wire, through the LED, through the yellow wire, through the resistor, and then back to the minus side of the battery (through the green wire, shown below), and the electricity flowing through the LED will turn on. 

Light on

And that's the basics of how electricity works. You have something push electricity through different electrical components, and those components use the electricity to do things. In this case, the LED turns electricity into light, and the resistor makes sure that there isn't too much electricity going through the LED. If there is too much electricity, the LED will burn out in a similar way to a light bulb that burns out. 

For those who wish to experiment, what do you think will happen if you use the resistor with more resistance instead of the middle one? Try it and find out!

Up next, connecting electrical components together with something other than a bunch of wires with clips: the solderless breadboard.