Electrostatics, sphere question.

[vkash]

Homework Statement

A spherical conductor A contains two spherical cavities. The total charge on the is itself zero. However, there is a point charge q_b at the center of one cavity and q_c at the center of other cavity. A considerable distance r away from the center of the spherical conductor, there is a another change q_d. Force acting on q_b , q_c, q_d, are F₁ ,F₂,F₃ respectively [assume all changes are positive.]then fill the dashed lines with <,>,=
F₁______F₂______F₃

Homework Equations

I use inly one equation in such questions that is

closed integral over closed surface(E.ds)=q/e.

It is gauss law.

The Attempt at a Solution

I have tried to do this with gauss law but failed. can you please help.

 

[WJSwanson]

Have you tried creating a visual representation to choose your Gaussian surfaces? The problem appears (as you've written it) to say that there is a pair of point charges in the cavities. The charge on a conductor aligns itself to negate any net electric field. What does this tell you about the charge configuration on the conductor if its net charge is 0?

What does this mean about the way the external charge q_d interacts with the other charges?

 

[vkash]

diagram of question