1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Electrical Potential between 2 points

  1. Jan 17, 2015 #1
    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 ]
    | |
    R2 R3
    | |
    [ /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. jcsd
  3. Jan 17, 2015 #2


    User Avatar
    Gold Member

    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.
  4. Jan 17, 2015 #3
    Code (Text):

                  |      |
                R2     R3
                  |      |
    Last edited by a moderator: Jan 17, 2015
  5. Jan 17, 2015 #4
    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.
  6. Jan 17, 2015 #5


    User Avatar

    Staff: Mentor

    What would you have to find out in order to determine the voltage drops across R1 and R4?
  7. Jan 17, 2015 #6
    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?
  8. Jan 17, 2015 #7


    User Avatar

    Staff: Mentor

    Sure. See what you can do with that.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted