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 much current is needed in an inductor to heat up water?

  1. Nov 9, 2012 #1
    1. The problem statement, all variables and given/known data

    How much current is needed in a 9.00mH inductor so that the stored energy will be enough to heat 285g of water from 20.0 degrees Celsius to the boiling point of 100 degrees Celsius? Specific heat of water is 4190 J/kg*Celsius.

    2. Relevant equations

    q = cm(change in T)

    3. The attempt at a solution

    q = (4190)(0.285g)(100-20) = 95532 J

    After this I got stuck, because I have no idea what to do with the inductance value and how to use it to find current. I looked at all the equations that my professor provided us, but I see no equations relating inductance, current, and energy. Any advice on how to begin would be much appreciated.
  2. jcsd
  3. Nov 9, 2012 #2


    User Avatar
    Homework Helper

    Last edited: Nov 9, 2012
  4. Nov 9, 2012 #3
    Thanks for the reply! In my work, I actually meant kg :) I did figure it out though, all thanks to you saying "energy stored in the inductor." I realized that I could use the equation U = 1/2 L (i^2), where U is the energy, and simply solve for i. For some reason, the stored energy part didn't register in my brain when I read the question, so thanks!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook