An electric dipole with dipole moment p is oriented along the y-axis.

a. Find an expression for the electric potential on the y-axis at a point where y is much larger than the charge spacing s. Write your expression in terms of the dipole moment p.

b. The dipole moment of a water molecule is 6.2 × 10^-30 C m. What is the electric potential 1.0 nm from a water molecule along the axis of the dipole?