A akimhaneul Full Member 7+ Year Member Joined Dec 2, 2015 Messages 438 Reaction score 23 Jun 6, 2016 #1 Members don't see this ad. I am confused about this question. Why is it that you use 1/2CV^2 in one situation and q^2/2C in the other? Thanks! Attachments Screen Shot 2016-06-06 at 6.36.42 PM.png 40.6 KB · Views: 75 Screen Shot 2016-06-06 at 6.36.52 PM.png 59.1 KB · Views: 65
Members don't see this ad. I am confused about this question. Why is it that you use 1/2CV^2 in one situation and q^2/2C in the other? Thanks!
theonlytycrane Full Member 10+ Year Member Joined Mar 23, 2014 Messages 2,127 Reaction score 2,276 Jun 6, 2016 #2 Q = VC PE (capacitor) = 1/2QV (but you can make substitutions using the equation above). When the battery is connected, V is constant so we want to use PE = 1/2V^2C. When the battery is disconnected, Q is constant so we want to use PE = 1/2Q^2/C. Upvote 0 Downvote
Q = VC PE (capacitor) = 1/2QV (but you can make substitutions using the equation above). When the battery is connected, V is constant so we want to use PE = 1/2V^2C. When the battery is disconnected, Q is constant so we want to use PE = 1/2Q^2/C.