Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Power to work of an inductor

  1. Feb 1, 2013 #1

    How can you get from the first expression to the second. I've done calculus, just need a fresher. I don't know how to deal with the dt/dt

  2. jcsd
  3. Feb 1, 2013 #2


    User Avatar
    Science Advisor

    What you have written is not clear. Is "Li" a single function or is this the constant, L, times the function i?

    If the latter this is easy. [itex]L\int_{-\infty}^t i(\tau) (di/d\tau)d\tau= L\int_{-\infty}^t i di = L\left[(1/2)i^2(\tau)\right]_{\infty}^t[/itex] which, if [itex]\lim_{\tau\to\infty} i(\tau)= 0[/itex] is [itex](1/2)i^2(\tau)[/itex]

    If Li is a single function, then it is NOT always true.
  4. Feb 1, 2013 #3


    User Avatar

    Staff: Mentor

    Yeah, L is the constant value of the inductance. i(t) is the current as a function of time.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Power inductor Date
I Power series - Different problem Mar 28, 2017
I Power series Mar 28, 2017
A Anyone can have the idea how to solve the log of a power ser Aug 15, 2016