The formula for calculating the electrostatic potential is given as:
U = (1/4πε0) (qp * qe/r)
where the variables are:
ε0 = permittivity of space = 8.854187817620 × 10^−12 A^2⋅s^4⋅kg−1⋅m−3
qp = charge of proton = 1.60217662 × 10-19 coulombs
qe = charge of electron = -1.60217662 × 10-19 coulombs
r = distance between the two = 54 pm = 5.4 × 10−11 m
So calculating for potential energy U:
U = (1/(4π*8.854187817620)) (1.60217662 × 10-19 * -1.60217662 × 10-19 / 5.4 × 10−11)
U = 5.33 x 10^-11 J
