#engineering basics

[certney]

I really want to learn how to build machinery but I don't even know where to start! I could use some input or anything really to get me going!

[eeunited]

Ohm's Law, What is it worth?

Let’s start with the basics of basics, Ohm’s law. V=RI what does it mean to you? As an Electrical Engineering student this means everything, even when it does not seem to be there it is. O yeah its obvious when you are working with a network of resistors and you need to calculate the voltage at a given node, but what about the gain of an op amp. All you need is Av=R1/R2 but where does this equation come from. If you don’t know, op amps like their two inputs to have the same voltage.  By applying a voltage to one of the inputs the output is going to do whatever it can to make the other input the same voltage. Now if you apply Ohm’s law to the feedback loop you will soon see that the feedback loop is simply a KVL voltage divider. Thus bringing back the Av=R1/R2. If a voltage of Vo is applied across these resistors in series causing a current in the loop so that the voltage across R1 will be the same voltage applied to the other input terminal. I know its not the best circuit to use but this is what I found looking for a quick example pic.