dub@pur-phy.UUCP (Dwight U. Bartholomew) (12/11/83)
From BILLW@SRI-KL Fri Dec 9 16:51:00 1983 < A simple thought experiment: < < consider two capacitors, one with a charge Q and voltage V, the other < uncharged. Connect them in parallel, so they each have charge Q/2, < but still voltage V. Now dissconnect them and connect them in series, < so that the total circuit has charge Q again, but Voltage V*2. Since < the end plates are now twice as far apart, they exert less force on < each other. < Bill W Nope, that's not true. Take a) put in parallel b) in series. a) Assuming both capacitors have the same capacitance... putting the charged one in parallel with the uncharged one will cause both to have charge Q/2 , but the voltage (via Q = C * V) across both will be V/2 . b) Putting them in series will cause the voltages to add, net result of V. The total charge will still be just Q/2. -Q/2| | Q/2 -Q/2| | Q/2 | | =====>> | | -----| |-----.-----| |---- | | | | | | | | CAP. A CAP. B When connected in series, the positive charge of capacitor A flows onto the "left-hand plate" of capacitor B and so the two charges cancel out. The net result is a capacitor with a charge of Q/2 and twice the plate separation (total capacitance = C/2). -Q/2| | Q/2 | | -----| |---- | | | | From the crusading terminal of: Dwight Bartholomew UUCP: {decvax,ucbvax,harpo,allegra,ihnp4,seismo,teklabs}!pur-ee!Physics:dub ARPA: dub @ pur-phy.UUCP