A small sphere has a charge of q = 2e, where e is the charge on an electron. (a) Determine the electric potential (in V) due to the charge at a distance r = 0.120 cm from the charge. Incorrect: Your answer is incorrect. Review the definition of electric potential at a point due to a point charge. Don't forget, the charge on an electron is negative. V (b) Determine the electric potential difference (in V) between a point that is 2r away and this point, that is V(2r) − V(r). Incorrect: Your answer is incorrect. Don't forget, we want V(2r) − V(r) and not V(r) − V(2r). Try writing your answer in terms of the expression for V(r) obtained in part (a). V (c) Determine the electric potential difference (in V) between a point that is r 2 away and this point, that is V r 2 − V(r). Incorrect: Your answer is incorrect. Don't forget, we want V r 2 − V(r) and not V(r) − V r 2 . Try writing your answer in terms of the expression for V(r) obtained in part (a). V (d) How would the answers change if the electrons are replaced by protons