Help with two electrical circuits please

[diegovmtj]

Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance

help would be much appreciated, thank you

http://imgur.com/trm1On0

http://imgur.com/a/KD3zr

 

[DrClaude]

What have you tried?

 

[diegovmtj]

i know that i have to use the KCL in each node, then use KVL to find the 4 equations so i can get the currents and voltages, the thing is that i don't know if the currents are going in or out of the nodes

 

[gneill]

i know that i have to use the KCL in each node, then use KVL to find the 4 equations so i can get the currents and voltages, the thing is that i don't know if the currents are going in or out of the nodes

It doesn't matter what you choose for the current directions, the math will "self correct" any bad choices so long as you stick to your choices while you write the equations. If a current direction was chosen incorrectly the result will be a negative value for that current, telling you that it flows in the direction opposite of your guess.

 

[CWatters]

+1

Choose/define an arbitrary direction for +ve current in each loop and mark on the diagram.
Work out what that current means for the polarity of voltage drops across resistors and mark those on the diagram.
Write KVL equations based on those voltages.
Write KVC equations for the nodes (perhaps assume current going into a node is +ve).
Solve the simultaneous equations
If a current turns out to have a -ve value then it's going the opposite way to the arrow on your diagram.