4. A hydrogen atom is in a state such that the proton and electron are separated by a distance of 0.5 x 10'10 m. The charge of the proton is 1.6 x 10'19 C, and the charge of the electron is -1.6 x 10'19 C. What is the magnitude of the electrical force of attraction , 2 between the two charges? You can use k = 9 x 109 NC"