Concepts to be used

Coulomb's formula for the electric force between two charges.

(1) F = k*q1*q2/r²

q1,q2 charges

r = separation between charges

k = constant

In SI units k is measured to be 8.98755*10^9 N-m²/C²

The constant k is often written as 1/4πε

_{0}.

The constant ε

_{0}is called the permittivity of the space and its value is

ε

_{0}= 8.85419*10^-12 C²/N-m²

q1 = q2 = -1.6*10^-19 C

r = 10^-10 m

F = [9*10^9(1.6*10^-19)²]/(10^-10)²

= 9*2.56(10^(9-38+20))

= 23.04(10^-9)

= 2.304*10^-8