Coulomb's Law Practice

Question

1. Two point charges, 3.13 x 10-6C and -4.47 x 10-6C are separated by 0.42m. 
2. Find the magnitude of the electrostatic force experienced by the positive charge

b. Is the magnitude of the force experienced. by the negative charge greater than, less than or the same as that experienced by the positive charge? Explain.

Answer 1

Coulomb's Law is F = (kq₁q₂)/r² where q₁ and q₂ are the charges in coulombs [C], r is the separation in meters [m], and k is Coulomb's constant 9•10⁹ [Nm²/C²]

a.) Substituting into the equation F = [(9•10⁹Nm²/C²)(3.13•10^-6C)(4.47•10^-6C)]/(.42m)² = .71N

Notice m² and C² both cancel leaving units of Newtons which are the proper units of force.

b.) .71N is the magnitude of the force. Each point charge experiences the same .71N magnitude of force, and the force is attractive because the charges have opposite signs so the forces are equal in magnitude but opposite in direction.