An early model of the atom, proposed by Rutherford after his discovery of the atomic nucleus, had a positive point charge, +Ze (the nucleus) at the center of a sphere of radius R with uniformly distributed negative charge -Ze. Z is the atomic number, the number of protons in the nucleus and the number electrons in the negative sphere.
a) Estimate the charged enclosed within a sphere with the nucleus at its center, and the radius of r, smaller than R.
b) Use Gauss' law to obtain the electric field inside this atom.
c) A uranium atom has Z = 92 and R = 0.10 nm. Estimate the electrostatic force that an electron would experience at r = R/2?