In what direction does the sphere move between two positive charges

[okgo]

Homework Statement

http://www.screencast.com/users/trinhn812/folders/Jing/media/8fe997e1-46e5-4033-a246-fbad0acb7162

Homework Equations

The Attempt at a Solution

I understand that in question 25, the conductor becomes polarized and its negative charges will be more attracted toward the bigger 5uC charge, but what's the reasoning for question 26? I don't get why the answer isn't C. Don't dieletrics kill the electric field?

 

[nickjer]

The dielectric can be polarized. So you can also have surface charges, but instead of them being free, they are now bound. Then you will get a surface charge density much like the conductor but much smaller in magnitude.

EDIT: Very similar to a balloon that you statically charge then hold it near a wall. The wall is a dielectric and will be attracted to the charged balloon.