k almost done, teacher didnt completely explain the problems

http://img370.imageshack.us/my.php?image=12wc.jpg

this one i didn't really get any but the Pcurrent

and

http://img370.imageshack.us/my.php?image=29pn.jpg

for this i got all the answers except I1 and P

oh btw my answers there some of em are wrong just pretend theyre all blank

I didn't notice first that the node voltages are given. This will make the calculations a lot easier.

The main equation you will have to remember is Ohm's law which is V=I*R where V=voltage, I=current, and R=resistance. To find, say in your first problem I1, all you have to do is find the voltage drop across R1 ( this can be done easily by subtracting the node voltages like the first from going from Va to Vb, some voltage is dropped across the resistor. To find that voltage drop you subract Va-Vb. Note that this is dependant on the direction you define your current to run.) then divide that with the resistance:

First solving for I from Ohm's law
V=IR
I=V/R

Using that into the problem:

I1= (Va-Vb)/R1

Similarily for the current running through R2 I'll call it Ir2 for now

Ir2=(Vb-Vc)/R2

Since the same current running through R1 is running through R2, those values should be equal I1=Ir2 .


The same applies to the second problem.