# KVL loop: Example wrong, or did I misunderstand?

1. May 27, 2013

### EngnrMatt

In my circuit analysis textbook, there is an example problem using a KVL loop. Though it seems relatively simple, I cannot understand the answer.

the loop consists of 3 voltages: -8, 12, and the unknown, Vr2. The polarities (clockwise) around the loop are respectively +,-,+.

The answer given is 4V for Vr2. I can see this being the case if the 8 wasn't negative, but if I apply algebra, the equation comes out as:

+ (-8) - (12) + Vr2 = 0

where Vr2 = 20

Am I treating the -8 wrong? Because if it were positive 8, I could understand Vr2 being 4, however, I am given to understand negative voltage is different from positive voltage.

2. May 27, 2013

### SteamKing

Staff Emeritus
A circuit diagram would be helpful.

3. May 27, 2013

### Simon Bridge

One of those is a voltage source while the other two are the volt drops over resistances huh?

4. May 28, 2013

### CWatters

Post the circuit diagram otherwise we are guessing what might be wrong.