Any help how to do the problem?
Use Green's reciprocity theorem to solve the following two problems:[hint-for distribution 1,use the actual situation;for distribution 2,remove q,and set one of the conductors at potential V0]
(a)Both plates of a parallel plate capacitor are grounded and a point charge q is placed between them at a distance x from plate 1.The plate separation is d.Find the induced charge on each plate.[Ans.Q1=q((x/d)-1)]
(b)Two concentric spherical conducting shells radii a and b are grounded,and a point charge q is placed between them at distance r.Find the induced charge on each sphere.

Hi neelakash,

I don't think it'll help you much for me just to tell you how to do these, but I can try to guide you through. So to start, what is the statement of the reciprocity theorem?

Forgive me as I was late...However,the Reciprocity theorem Griffiths refers to in this context is int{rho1*phi2 dV}=int{rho2*phi1 dV}where rho means volume chrage density and phi is the potential.

Ok, great, now you need to identify the relevant charge densities and potentials. Take (a) for example, in situation 1 you have two grounded plates with a point charge between them, and in situation 2 you have no point charge but one of the plates is held at a voltage.

Now in situation 1 you don't know the charge on either plate and the potential is generally complicated, but you do know the plates are at zero voltage. In situation 2, the potential everywhere is easy to calculate. Furthermore, any charge in situation 2 can only reside on the plates, but that's the one place we know phi1! So you're looking for rho1 on the plates, you can find phi2 easily, and I just explained how rho2*phi1 = 0, so now see if you can use the reciprocity theorem to find what you want.