# Ohm's Law: Test tomorrow, HELP!

#### Ubiyca

Joined Sep 18, 2007
1
Hey all

I have a very important test tomorrow all on Ohm's Law.

I know how to do the "basics" but I get confused with for example.. if they list a certain voltage on a circuit, and you gotta figure out how that voltage divides into the rest of the circuit... and also those huge mixed circuits where you gotta find the total resistance and etc..

Any sites with some great exercises so I could get some great practice for the test? also.. any site with great info? (I read a lot from this site, great site) also.. any other advice u can give me.. go for it. much appreciated

#### bloguetronica

Joined Apr 27, 2007
1,533
Here it is: R = V / I (Ohm's law)

Based on that and knowing that in a resistor series association the current is the same for each transistor and it is determined by the sum of all resistances, you can calculate the voltage across each resistor. In a paralel association you know that the voltage across is the same for all resistors, and based on the Ohm's law you can calculate the current through each resistors. You can analyse more complicated circuits using the laws:

Rs = R1 + R2 + ... + Rn (series association)
Rp = 1 / (1 / R1 + 1 / R2 + ... + 1 / Rn) (paralel association)

That's it!