Basic Formulas

[Morbid]

Hi, i'm having a test on electricity next week so i just wanted to ask
if some of u guys have a web site or some reference to read
about ohm law formula and some expentions for:
* Watt
* Resistance
* Voltage
* Current
in parralel/serial and JOINED circuit.

and also about calculation JOINED circuit with 3 power sources and common resistors.
like :
e1 = I1(r1+r2+r3) - I2(r3) - I3(r2)
e2 = -I1(r1) + I2(x,x,x) - I3(x)
....

thanks!
Chen

[Sch3mat1c]

Hmm... should I give in... or should I tell him to be a good boy and Google it (or grab a piece of paper, R = V/I and P = V*I and figure them out) himself...

Tim

[cpemma]

Originally posted by Morbid
...and also about calculation JOINED circuit with 3 power sources and common resistors.

Kirchoff would be a word to google with...

[Sch3mat1c]

Actually, that's superposition something or other. I don't actually know anything about it but I saw a thread about it elsewhere.

Tim

[djembe]

Superposition is quite simple. Look at current/voltage sources one at a time. Replace other current sources with an open-circuit, and replace other voltage sources with a short-circuit. Solve for these simpler circuits individually, and when you get whatever value you are looking for, add the simple answers together to get the total value.

Here is an example I found in google:

Superposition example

Hope it helps