What is the strength of the electric field ep 9.0 mm from a proton?

The working equation to be used for this is written below:

E = kQ/d²

where

E is the electric field

k is a constant equal to 8.99 x 10⁹ N m²/C²

Q is the charge

d is the distance

The charge for a proton is equal to 1.6021766208*10⁻¹⁹ C. Substituting the values:

E = (8.99 x 10⁹ N m²/C²) (1.6021766208*10⁻¹⁹ C) / (0.009 m) ²

E = 1.778*10⁻⁵ N/C