An early model of the atom, proposed by Rutherford after his discovery of the atomic nucleus, had a positive point charge +Ze+Ze (the nucleus) at the center of a sphere of radius RR with uniformly distributed negative charge −Ze−Ze. ZZ is the atomic number, the number of protons in the nucleus and the number of electrons in the negative sphere. a. Show that the electric field inside this atom is:Em= Ze/4πeo (1/r²- r/R³) b. What is Eat the surface of the atom? Is this the expected value? Explain. c. A uranium atom has Z=92 and R: 0.10 nm. What is the electric field strength at r=1/2R.