1. The problem statement, all variables and given/known data A charged spherical insulating shell has inner radius a and outer radius b. The charge density on the shell is ρ. What is the magnitude of the E-field at a distance r away from the center of the shell where r < a? 2. Relevant equations Gauss' Law 3. The attempt at a solution I read through the Gauss' law chapter in my textbook, and it stated that the internal electric field of such a charged insulator is zero. Therefore, I know the answer is 0 but I do not know why. Any explanation as to why this answer is correct would be appreciated. Thanks.