Calculating Potential Difference in Parallel Circuits

AI Thread Summary
The discussion focuses on calculating potential differences in a parallel circuit involving points A, B, and C. The initial calculation for the potential difference across AB is presented as 3V, but there is confusion regarding the total resistance between B and C. Participants clarify that the total resistance for resistors in parallel must be calculated using the appropriate formula, which was not initially applied correctly. The correct approach involves finding the equivalent resistance to determine the potential differences accurately. Understanding the principles of parallel circuits and equivalent resistance is essential for solving the problem correctly.
looi76
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Homework Statement


http://img241.imageshack.us/img241/1087/09052008hf9.png
What is the potential difference across (i) AB (ii) BC.

Homework Equations


??

The Attempt at a Solution


(i) \frac{200}{400} \times 6 = 3V

Is this right? :confused:
 
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I think the easiest way to do this would be to use equivalent resistances to find the current. After that it is very easy
 
I didn't understand...
 
Hi looi76,

We know the total resistance between A and B is 200 ohms. What is the total resistance between B and C?
 
The total resistance between B and C is 100 because they are connected in parallel. So, \frac{200}{(100 + 200)} \times 3 = 2V

Is this correct?
 
No, that is not the total resistance between B and C. They are both in parallel. What is the formula for resistance connected in parallel?
 
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