Static electricity and method of seperating

[winston]

The figure below shows an electrostatic method of separating conducting and non-conducting spheres

Why do the conducting spheres fall off from the roller while the non-conducting spheres have to be scrapped off?



Thanks for the help.
Cheers,
Winston

 

[Astronuc]

What is the significance of conducting?

 

[winston]

Not too sure... Is the answer something about non-conductors holding the charge at the surface but charges in conductors flow throughout the material. But I thought that all the spheres will become negatively charged upon contact with the negatively charged roller.

HELP. THANKS

 

[Astronuc]

Is the answer something about non-conductors holding the charge at the surface but charges in conductors flow throughout the material.

Yes.

For the non-conducting material, the mobile charges (electrons) do not move so readily, so electrons will not flow onto the positively charged non-conducting material

In the 'conductor', the mobile charges (electrons) readily flow thus reducing the positive charge while the conducting material traverses the arc.