F = 1440 N. The repulsion force between two identical charges, each -8.00x10⁻⁵C separated by a distance of 20.0 cm is 1440 N.
The easiest way to solve this problem is using Coulomb's Law given by the equation [tex]F=k\frac{|q_{1}*q_{2}|}{r^{2} }[/tex], where k is the constant of proportionality or Coulomb's constant, q₁ and q₂ are the charges magnitude, and r is the distance between them.
We have to identical charges of -8.00x10⁻⁵C, are separated by a distance of 20.0 cm, and we need to know the force of repulsion between the charges.
First, we have to convert 20.0 cm to meters.
(20.0 cm x 1m)/100cm = 0.20 m
Using the Coulomb's Law equation:
[tex]F = 9.00x10^{9}\frac{Nm^{2}}{C^{2}} \frac{|-8.00x10^{-5}C*-8.00x10^{-5}C|}{(0.20m)^{2} }[/tex]
[tex]F = 9.00x10^{9}\frac{Nm^{2}}{C^{2}}(1.6x10^-7\frac{C^{2} }{m^{2} } })\\F = 1440N[/tex]