Section #2 – Resist If You Must
Understanding what resistance is, is just as fundamental as understanding what voltage and current are. In fact, they are all related! Reference Ohms Law
It’s hard to mention resistance without mentioning Ohms Law, which is why it astonished me that this section doesn’t even reference it once…. Voltage is equal to Current times Resistance V=IR. With some basic algebra you can see that you can also figure out current and resistance by dividing the voltage by what you have.
Another reason that not mentioning Ohms Law is astonishing to me is because you need to use resistors to prevent destroying an led. Otherwise you will have to much current and voltage passing through your little bulb and blow it out.
The three projects in this section are pretty cool. They all demonstrate different ways of applying resistance to your circuits.
The first project has you building an array of LED’s with varying resistance on them. This demonstrates how resistance affects the brightness of the LED. It’s good to see a physical representation of what is happening because most components will not react so clearly when resistance is added or taken away.
Project number two is the featured photo for this article. Project two introduces you to the potentiometer (POT) and teaches you about different consumer devices that contain POTs. The long and short of it is, as you turn the potentiometer the resistance increases. It continues to increase until there is to much resistance to allow current to pass though.
I love working with potentiometers in personal projects and this is a very good thing to know how to use to it’s fullest.
The final project in section two uses a light dependent resister. That’s right, a light dependent resister, meaning it needs light to change it’s state. With light shining on the resistor it allows current to pass through the circuit. However, when you remove the light, the resistance increases and the light dims. A very nifty tool.
This chapter was pretty good. I am a little disturbed by the lack of mention of Ohms law but it is what it is I guess. They wanted to keep the book easy to consume. I’m just afraid they left out something very important.
On to the next!
Author: Anthony Russell
Professional .NET Developer