Assignment:
Question 1. If the electric ?eld in some region is given (in spherical coordinates) by the expression
E(r) = (A* r(hat)+ B sin θ cos φ* φ(hat)) /r ,
where A and B are constants,
what is the charge density?
Question 2. A metal sphere of radius R, carrying charge q, is surrounded by a thick concentric metal shell (inner radius a, outer radius b). The shell carries no net charge.
(a) Find the surface charge density σ at R, at a, and at b.
(b) Find the potential at the center, using in?nity as the reference point.
(c) Now the outer surface is touched to a grounding wire, which lowers its potential
to zero (same as in?nity). How do your answers to (a) and (b) change?
Question 3. What is the force of attraction between q and a grounded conducting sphere?