Field on a spherical cavity - Corrected Exercises Gauss Theorem


A sphere of radius R, carrying a load volume r that is uniformly distributed throughout the volume which occupies  the exception of a radius of cavity a. The center of this cavity is the distance of the center of the sphere. The cavity is empty loads.
Using the Gauss theorem and the principle of superposition, calculate the field at all points of the cavity.
  what is remarkable?




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