How Does Gauss's Law Apply to Nested Spherical Shells with Charges?

[stroperica]

Homework Statement

A small conducting spherical Shell (#1) with inner radius a and outter radius b is concentric with a larger conducting spherical shell (#2) with inner radius C and outter radius d. The inner shell has a total charge (-3Q), and outter shell has a charge ( +5 Q).

a) Use Gauss's law to find the electric field ( magnitude and direction) in terms of Q and r for

i) r<a;
ii) a<r<b;
iii) b<r<c;
iiii) c<r<d;

b) determine the surface charge density on the inner and outer surfaces of both shells.

The Attempt at a Solution

Electric field for i and iii is zero?

 

[stroperica]

Here is the figure for the exercise.
THANK YOU!

 

[Redbelly98]

Welcome to Physics Forums

The Attempt at a Solution

Electric field for i and iii is zero?

Can you show your work? You are supposed to make use of Gauss's law here.