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?

 

[sardar]

I would like to clarify that the formula provided, F=k[(q1*q1)/r^2], is not correct. The correct formula for electrostatic force between a point charge and a dielectric ball is F=k[(q1*q2)/r^2], where q1 is the charge of the point charge, q2 is the charge of the dielectric ball, and r is the distance between the two charges.

Now, to answer the question, if the value of the point charge is doubled, the electrostatic force acting on the dielectric ball will also double. This is because the electrostatic force is directly proportional to the magnitude of the charges involved. So, if one charge is doubled, the force will also be doubled.

Furthermore, the presence of a dielectric material does not change the value of the electrostatic force. However, it can affect the electric field and the capacitance of the system, which can indirectly impact the force. A dielectric material has a higher permittivity than air, which means it can store more charge and thus increase the capacitance of the system. This can lead to a larger electrostatic force.

In conclusion, doubling the value of a point charge will double the electrostatic force on the dielectric ball, and the presence of a dielectric material may indirectly affect the force through changes in electric field and capacitance.