# Electrical Potential between 2 points

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1. Jan 17, 2015

### UTK_James

Mentor note: Member warned about posting a question without the template
1. Find the electrical potential between A and B given that R1=R2=R4=100 Ohms; Power dissipated by R3 is 200 mW at 9 Volts

[ code ]
A---------R1-----------*-------------------
| |
R2 R3
| |
B---------R4----------*--------------------
[ /code ]

I have no clue where to even start on this problem.. So any help will be greatly appreciated.

Last edited by a moderator: Jan 17, 2015
2. Jan 17, 2015

### phinds

Take the extraneous spaces out of your code tags so that your diagram shows up correctly.

Also, you HAVE to show some effort, as per the forum rules. If you don't know ANY formulas relating to voltage, current, resistance, and power, then you should not be attempting the problem.

3. Jan 17, 2015

### UTK_James

Code (Text):

A-----R1------*-------
|      |
R2     R3
|      |
B-----R4------*-------

Last edited by a moderator: Jan 17, 2015
4. Jan 17, 2015

### UTK_James

I know the dissipating power is equal to v^2/R so that would be .2=9^2/R, with the R value being 405 ohms, but from there I have no clue where to go from there.

5. Jan 17, 2015

### Staff: Mentor

What would you have to find out in order to determine the voltage drops across R1 and R4?

6. Jan 17, 2015

### UTK_James

You need the current across those two resistors to find the voltage drop. Would that current be the same current that flows through R2 and R3?

7. Jan 17, 2015

### Staff: Mentor

Sure. See what you can do with that.