The ammonia molecule NH3 has a permanent electric dipole mom

The ammonia molecule NH₃ has a permanent electric dipole moment equal to 1.39 D, where 1 D = 1 debye unit = 3.34 10³⁰ C · m. Calculate the electric potential due to an ammonia molecule at a point 56.0 nm away along the axis of the dipole. (Set V = 0 at infinity.)

Solution

the potential due to dipole is

V = k p cos theta/r^2

= ( 9.0 * 10 ^9 ) ( 1.39 * 3.34 * 10 ^-30 C) cos 0 /( 56 * 10 ^-9 m)^2

=13.3 * 10 ^-6 V