1. The problem statement, all variables and given/known data http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys212/oldexams/exam2/fa06/fig17.gif [Broken] After a very long time with both switches in the closed position, switch S2 is reopened. How long does it take for the charge on capacitor C2 to drop to 1/e (36.8%) of its fully-charged value (i.e. of the value it had just before S2 was reopened)? 2. Relevant equations Time constant = RC 3. The attempt at a solution I try to find the total resistance, but am not sure how. I am not even sure what it means by "drop to 1/e (36.8%)". Does it mean 36.8% of the total charge?