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: Entropy of running water around a resistor

  1. Aug 27, 2011 #1
    1. The problem statement, all variables and given/known data
    An electric current of 10A runs for 1 minute through a 20 ohm Resistor which is maintained at 10 degC by being immersed in running water. What are the entropy changes in a) the resistor b) the running water c) the universe

    2. Relevant equations

    P = I2R

    dS = dQ/T

    3. The attempt at a solution

    For a) there is no change in the entropy as it is work done by the resistor, not heat.

    b) I've calculated P = 2000W = 2000J

    The problem I'm having is formulating the path between the initial and final states of the system because of the constant temperature. I'm also not sure if I'm using the right equation?

    c) This will be the same as the answer for b) I think.
  2. jcsd
  3. Aug 27, 2011 #2
    Figured it out!

    Forgot to convert the temperature to kelvin and then got everything written down in a mess!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook