1. Not finding help here? Sign up for a free 30min 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!

Help finding battery voltage.

  1. Sep 17, 2008 #1

    crh

    User Avatar

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

    In the circuit shown, the 33-ohm resistor dissipates 0.50 W. What is the battery voltage?

    [​IMG]

    2. Relevant equations

    I am pretty sure that I use the equation V=IR, but I am not for sure how to go about using the 0.50W in the equation. At first I thought that I used P=IV for electric power, but I am just confused.

    3. The attempt at a solution

    I don't even know what equation to exactly use because the watts are throwing me off.
     
  2. jcsd
  3. Sep 17, 2008 #2

    LowlyPion

    User Avatar
    Homework Helper

    You should know from Watts = V*I and V= I*R that Watts = I2R
    Watts is your equation for P = Power.

    So knowing the watts of a resistor lets you figure out the current.

    Knowing the current and figuring the equivalent resistance for the 3 resistors through the V=I*R tells you the voltage of the supply.
     
  4. Sep 17, 2008 #3

    crh

    User Avatar

    thank you, I figured it out with your help.
     
  5. Sep 17, 2008 #4

    LowlyPion

    User Avatar
    Homework Helper

    Good luck then.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?