Electric charge on hollow spherical conducting shells Gauss's Law(?)

[offbeatjumi]

There are two spherical hollow conducting shells, one inside the other. The outer shell has a radius 4 times that of the inner shell. There is a switch connecting the two shells, which is for the moment, open. Both shells have a positive charge (inner shell = +20nC and outer shell = +60nC.

When the switch is closed... can someone explain why all the charge moves to the outer shell? The fact that there is a conducting wire (switch) connecting the two spheres makes it confusing for me to apply a Gaussian surface.

Thanks =)

 

[Mindscrape]

The electric field inside a conductor is zero. Basically what you are doing by connecting the outer sphere and the inner sphere is just making a really strange inner cavity. To maintain the fact that the field inside the whole conductor, the two shells, is zero all the positive charges will have to go to the outer shell. This is kind of a radical example, but as I said, just think of connecting them as making a big conductor with a really weird cavity.