1. The problem statement, all variables and given/known data Here's a link to the circuit: http://tinypic.com/view.php?pic=30js0wp&s=6 Initial current, t, and final current are given. Seeking time constant. 2. Relevant equations I=Io (1-e^(-t/T)) where Io is initial current and T is the time constant. This is an RL circuit right? 3. The attempt at a solution I used the equation above to calculate time constant, is that correct?