A spherical conducting shell of inner radius a and outer radius b carries a total charge +Q distributed on the surface of a conducting shell (figure a). The quantity Q is taken to be positive.

Suppose the charge at the center is now increased to +7Q, while the charge at the surface of the conductor is changed to +3Q. (Use the following as necessary: ε₀, π, Q and r.)

1. Find the electric field exterior to the sphere, for r > b.

2. What's the electric field inside the conductor, for a < r < b.

3. Find the charge distribution on the conductor. (inner surface)