1. The problem statement, all variables and given/known data Imagine that you have a light-bulb that has a resistance of about 10 Ω and that can tolerate a maximum voltage of 3 V. Imagine that you want to connect this to a charged capacitor large enough to keep the bulb glowing reasonably brightly for more than 10s. Roughly what should the capacitor's capacitance be? 2. Relevant equations I=(dQ)/(dt) R=([tex]\Delta\phi[/tex])/(I) C=(Q)/([tex]\Delta\phi[/tex]) 3. The attempt at a solution It looks like I need to know something about the charge to solve this, or I need to cancel it out, but I can't seem to make any headway. How can I solve for the capacitance without Q? Am I missing something obvious?