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: How to find emf

  1. Dec 19, 2012 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    Current = (emf)/(resistance)

    Capacitance = (Charge)/(voltage)

    Stored energy = (Capacitance)(Volt ^ 2) /(2)

    3. The attempt at a solution

    I need to find current and resistance so I can find emf.

    capacitance = (charge)/(volt)

    stored energy = (charge(voltage)/(2)

    25 J (2) /(3C) = 50/3

    voltage is 50/3 or 17 V.
  2. jcsd
  3. Dec 19, 2012 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    This has nothing to do with either resistance or capacitance.

    You have a battery rated at "emf" volts and you have sucked 3 C (coulombs) of charge out of it. How much energy is that?
  4. Dec 19, 2012 #3
    thats right! volt is measured in joules per coulomb! got it thanks!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook