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: Finding time constant of current decay in closed circuit

  1. Sep 3, 2008 #1
    Hi this is my first post so please be nice :)

    1. The problem statement, all variables and given/known data
    The problem has been set up that a circuit containing a resistor and switch is being driven by a power source of unkown potential. The switch is flick to short the power source leaving only the resistor in a closed loop.
    Calculate the current decay.
    Initial current = 100A
    Resistance = 1n[tex]\Omega[/tex]

    2. Relevant equations

    Power = I2R

    3. The attempt at a solution

    I'm not too sure. The power generated, and hence the heat loss can be found to be 1e-5W so thats 1e-5 Joules per second of heat loss.

    I'm not sure if we have enough information. Current decay involving inductance or capacitance is well known but just a resistor in a circuit of 'ideal' conductors?

    I'm assuming it is an exponential decay of form I=I0e-t/[tex]\tau[/tex] but finding the decay constant is proving tricky. Any advice????

    Thanks in advance.
  2. jcsd
  3. Sep 3, 2008 #2
    Sorry, posted in wrong forum. Please delete.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook