A hollow, conducting sphere with an outer radius of 0.240 m and an inner radius of 0.200 m has a uniform surface charge density of +6.47 × 10−6 C/m2. A charge of -0.900 μC is now introduced into the cavity inside the sphere.
a. What is the new charge density σ on the outside of the sphere? Express your answer with the appropriate units.
b. Calculate the strength of the electric field E just outside the sphere. Express your answer with the appropriate units.
c. What is the electric flux through a spherical surface just inside the inner surface of the sphere? Express your answer with the appropriate units.