Thursday, August 4, 2011
Intro into Electronics Part 1 DC
First we should go over some definitions:
Voltage-V it is energy per unit charge measured in volts
Current- I it is the rate of flow of charge measured in amperes/amps
Resistance- R it is the property of the material that hinders the current measured in ohms
If you have ever taken a class in electronics you will recognize this next image it is the water analogy.
This image pretty much explains Voltage resistance and current. So now, lets go over a couple of equations.
1. Ohm's Law V=IR so Voltage = Current x Resistance. This is the most basic equation in electronics. So for a given wire size (with known resistance), if the voltage is increased then the current must also be increased.
2. Power P=IV or Power = Current x Voltage. You can substitute Ohm's law and get P=I^2 R and so on. Power is either absorbed by an element or delivered by an element. Whether Power is delivered or absorbed depends on the passive sign convention.
THE PASSIVE SIGN CONVENTION
The passive sign convention is very important in circuit analysis. If you do not follow it you will get wrong voltages and currents and ect... in your calculations.
The passive sign law states: When current enters the positive terminal then the element absorbs power. If the current leaves the positive terminal then the element delivers power.
That is all I am going to cover for now. Next time I will go over some basic ways to analyze simple circuits. (preview KCL and KVL) and I may also throw in a introduction to a component. Always open for questions and corrections I am a student and not perfect but would like to share what I have learned