# Magnitude of Potential Difference Between Two Points

1. Homework Statement [/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

## Homework Equations

I know Δv=IR and Ampere/Volt makes an Ω

## 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!

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## Answers and Replies

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

gneill
Mentor
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?

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

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

Haha, lewando, yes please!

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!

Well then take a look at the following two websites:
http://www.allaboutcircuits.com/vol_1/chpt_5/1.html (for a definition of series/parallel)
http://en.wikipedia.org/wiki/Series_and_parallel_circuits (for how to combine them)

Give them a read and come back with any questions.

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!