Capacitors reconnected (finding charge and potential)

[luigidorf]

Homework Statement

Homework Equations

Q = CV

The Attempt at a Solution

It's already solved for me; I just don't understand it.

In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?

 

[gneill]

In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?

The charges Q1 and Q2 are of different sizes. They don't completely cancel. They leave charge q remaining uncancelled.

 

[luigidorf]

Ah there it is. Thanks!