Basic Electricity

Here's a post that's mostly for my own studies, but I hope others will find it useful.

Current is the flow of electrons. It is represented by the letter I. Current is measured in Amperes, which is represented by the unit A. Current is measured with an ammeter.

Voltage is the electro-motive force of electricity. It is represented by the letter E. Voltage is measured in Volts, which is represented by the unit V. Voltage is measured with a voltmeter. Voltage is measured from a reference voltage, which is usually ground. Voltage also has a polarity; positive polarity attracts electrons, while negative polarity repels them.

Resistance is the impedance of current. It is represented by the letter R. Resistance is measured in Ohms, which is represented by the unit Ω. Resistance is measured with an ohmmeter.

Ohm's Law defines the relationship among current (I), voltage (E), and resistance (R).

R = E / I

You can solve the equation for the others with some quick math.

E = R * I
I = E / R

Power is the product of voltage (E) and current (I). It is represented by the letter P. Power is measured in Watts, which is represented by the unit W. Power is not measured directly and must be calculated.

P = E * I

Again with some quick math.

E = P / I
I = P / E

Using the equations from Ohm's Law, we can substitute values for voltage (E) and current (I) in to the Power equation. Since E = R * I, we can say that P = (R * I) * I or RI^2. Also, since I = E / R, P = E * ( E / R), or E^2/R.

P = E^2 / R
P = R * I^2

Introductions

Hi. My name is Aaron, and I'm taking some time off from my career studies to get my ham radio licenses. I have a blog on networking stuff at my own place which I use to make study notes, so, as I go through my studies here, I thought I would do the same.

Naturally, I'm going to start with the technician license, so keep an eye out for the basic stuff that all you Elmers already know. For the record, I just read the term "Elmer" in a book and have no clue when to use it appropriately. :)

Talk to you guys on the air soon. I'm sure my jargon will be better in time.