1. The problem statement, all variables and given/known data A 10-µF capacitor is charged by a 10-V battery through a resistance R. The capacitor reaches a potential difference of 4 V in a period of 3 s after the charging began. Find the value of R. 2. Relevant equations c=q/v q=CE(1-e^-t/RC) i=(E/R)e^(-t/RC) 3. The attempt at a solution I found the charge on the capacitor when its at 4 volts and got 4.0 * 10^-5 C. I then tried to plug this into the equation for a capacitor charging, but I dont know the time at which the capactior is at 4 volts. At this point, I attempted finding another equation, so I could attempt a system of 2 equations with 2 unknowns. I tried to use the current in a capactor charging equation, but I ended up getting infinitely many solutions. I am not entirely sure how to approach this problem.