Question

A hollow, spherical, ideal insulator (R=0.075m) has a net charge of +3.75μC, with the charge is distributed uniformly throughout its volume

A- Calculate the total electric flux though a “Gaussian” sphere (with radius r=0.065m) centered on the center of the charged sphere.

B- Find the magnitude and direction of the electric field at a point, r=0.115m, directly below the center of the sphere.

Answer 1

Answer :--

(A) electric field at r = 0.065 m < R (= 0.075)

• since it is hollow therefore the total charge enclosed by the gausian sphere of radius 0.065 (which is <0.075 ) = 0
• so the electric field = 0

(b)--

• no in this case r >R  
• so applying the gauss law
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• ​​​​​​​ far from the centre .