# Homework Help: Magnitude of Potential Difference Between Two Points

1. Mar 10, 2013

### anomalocaris

1. The problem statement, all variables and given/known data[/b]

So I found this problem online, and I really do not know how to go about solving it! My professor has done similar problems in class, but it's still a little confusing.

A current of 1.2 A flows from A to B. Therefore, the magnitude of the potential difference between points A and B is approximately

2. Relevant equations
I know Δv=IR and Ampere/Volt makes an Ω

3. The attempt at a solution

Well, the image attached already gives the answer, it should be 6.0 V. The current is given (1.2 A), so I'm guessing by the units that I must multiply something with Ω to get Volts. Should I add up the resistors?

Thank you!

Last edited: Mar 10, 2013
2. Mar 10, 2013

### lewando

To do this problem, you are going to need to be able to "add" resistors in parallel and series. Need help with that?

3. Mar 10, 2013

### Staff: Mentor

Sure. Find the equivalent resistance between points A and B. Then see what potential drop occurs across it due to the given current value.

4. Mar 10, 2013

### anomalocaris

Would we consider the two 6Ω resistors parallel? And if so, the potential difference there is the same? We are getting to the point where I just smile and nod during the lecture even though I am completely lost!

5. Mar 10, 2013

### lewando

6. Mar 10, 2013

### anomalocaris

Thank you so much! I just had an epiphany and this is all way less complicated! Thank you to all who replied. And thank you so much, lewando. I wasn't taking the reciprocals of the resistances and so I was adding them incorrectly, but now it all makes much more sense. I ended up with an R_eq of 5Ω, which when multiplied by 1.2 A yields a potential difference of 6 V. Thank you so much!