# Homework Help: Electric Circuits, Kirchhoff's Rules

1. Sep 22, 2008

### yayirunin2car

The question: Suppose point A is grounded (V = 0) in Figure 21-36, in which script e = 16 V and R = 11 . Find the potential at points B and C.

Here is the diagram:
http://www.webassign.net/walker/21-35alt.gif

I'm pretty sure that I have to use Kirchhoff's rules in order to solve this problem, but I'm afraid that I've been reading them over and over and don't completely understand them. Especially with this 'grounded' stuff. Does that mean that I just ignore that part of the circuit, where 6.2 and 11 ohm are? I guess I need a little bit of guidance in how to start solving this.

Last edited: Sep 22, 2008
2. Sep 22, 2008

### LowlyPion

You can develop the equivalent resistance for the circuit to make it a bit easier. Then you have the current flowing through nodes A, B, and C. The voltage potentials are then determined easily.

3. Sep 22, 2008

### yayirunin2car

Thank you very much! I got the correct answers - only I had to change point C into having a negative voltage. I don't exactly understand why it's negative though.

4. Sep 22, 2008

### LowlyPion

The initial condition of the problem is that node A is held at ground.