Circuit Problem

[invidia]

I'm having a really hard time trying to solve this circuit problem. Here's a crappy drawing of it: HERE


The textbook I have doesn't even explain and talk about circuits withe more than 2 voltage sources. I tried googling for info about circuits and voltage and got nothing. It's the 2 voltage sources that's throwing me off.

The problem asks for the current in the circuit. Correct me if I'm wrong but I can somewhat get the current if I treat it like a voltage divider but that second voltage source is pissing me off. I don't know what to do with it.

 

[KLin]

Ohm's law?

 

[Leros]

I'm really bad with this stuff. I'm taking the second Circuity Theory course right now and I hate it. Anyway, can't you just apply KCL and KVL?

 

[MBrown]

KVL (Kirchoffs Voltage Law)

 

[Jeff7]

Where in the circuit does it want the current? If V1 != V2 or R1 != R2, then you're going to have different currents in different parts of the circuit. In that case, I think Kirchoff's Rules may apply.

 

[invidia]

Originally posted by: Jeff7
Where in the circuit does it want the current? If V1 != V2 or R1 != R2, then you're going to have different currents in different parts of the circuit. In that case, I think Kirchoff's Rules may apply.

V1 = V2 and R1 = R2. But would I treat the resistors in parallel or in series?

 

[Jeff7]

Hm.....well it still might be Kirchoff's Rules then. It's sad, really, I just had this stuff last semester, and aced it on the tests, and I'm already drawing a blank on how to do it.

 

[Pepsi1337]

Here is the answer. Sorry for the blurry shot but I'm lazy and the answer is for free, you know.

http://img265.imageshack.us/img265/3880/img0879yv4.jpg

 

[esun]

Pepsi got it right. You're thinking too hard. You don't need voltage dividers or parallel/series concepts, just basic Ohm's Law and KCL.

 

[Toastedlightly]

Kirchoff's loop rule!

 

[invidia]

ahh, I see. I tend to over think on many of these problems. It's why I fail so much. Thanks pepsi

 

[BrownTown]

Gah, the urge to make a bastardly response here is too high . I'll simply say that we had much harder circuit problems than this in high school physics and that any problem not involving transistors or the Laplace transform should never be called "really hard".

For any DC problem like this just remember to do nodal analysis and then solve the resulting equations (unless your teachers are bastards they'll let you use calculators when you start getting to 4+ simultaneous equations).

 

[TuxDave]

Originally posted by: invidia
ahh, I see. I tend to over think on many of these problems. It's why I fail so much. Thanks pepsi

The first thing you need learn is how to approach problems you have never seen before. My first step is always identifying what is known and what you can get from that data. Then once all the info is on the page to start figuring out what you can do with it. In circuits sometimes it's easier to look at voltages, sometimes easier to look a currents and so swapping things around helps a little.

 

[esun]

That *is* a bastardly response. Your urge to not make one failed, especially because the OP never called the circuit "really hard".