Electrostatic force between point charge and dielectric ball.

[dark_vader93]

At a certain distance from a point charge q there is small, dielectric
ball. How would change the value of electrostatic force
acting on the ball, if the value of a point charge would be doubled?
According to F=k[(q1*q1)/r^2] there would be no force on the dielectric ball, because his resultant charge is 0. Is it so? Please hint.

 

[Matterwave]

Are you sure that the dielectric ball won't be polarized in the presence of the charge?

 

[dark_vader93]

Truth. So the force would double, wouldn't it?

 

[Matterwave]

I would think that doubling the charge would proportionately increase the polarization of the sphere. I would suspect, based off intuition, that the force would more than double.

A full treatment of the problem should be that you find the E fields outside and inside the dielectric ball, and then use stress tensor to get F=TdA. What level of E&M are you in?