Answer:
1. The electric force between two charges is given by the equation:
F = k * (q1 * q2) / r^2
where F is the force, k is the Coulomb's constant (8.99 x 10^9 N * m^2 / C^2), q1 and q2 are the charges, and r is the distance between the charges.
q1 = 10e-6 C and q2 = 10e-6 C
r = 5 x 10^-2 m
F = 8.99 x 10^9 N * m^2 / C^2 * (10e-6 C * 10e-6 C) / (5 x 10^-2 m)^2
F = 8.99 * 10^9 * 10^-12 / 25 * 10^-4
F = 0.36 N
2. The electric force between two charges is given by the equation:
F = k * (q1 * q2) / r^2
where F is the force, k is the Coulomb's constant (8.99 x 10^9 N * m^2 / C^2), q1 and q2 are the charges, and r is the distance between the charges.
q1 = -5.6e-6 C and q2 = 10.6e-9 C
r = 7m
F = 8.99 x 10^9 N * m^2 / C^2 * (-5.6e-6 C * 10.6e-9 C) / (7 m)^2
F = -4.4*10^-5 N
3. The electric force between two charges is given by the equation:
F = k * (q1 * q2) / r^2
where F is the force, k is the Coulomb's constant (8.99 x 10^9 N * m^2 / C^2), q1 and q2 are the charges, and r is the distance between the charges.
q1 = -7.8e-6 C and q2 = -7.8e-6 C
r = 2.3 x 10^-2 m
F = 8.99 x 10^9 N * m^2 / C^2 * (-7.8e-6 C * -7.8e-6 C) / (2.3 x 10^-2 m)^2
F = 8.99 * 10^9 * 7.8^2 10^-12 / (2.310^-2)^2
F = 4.58 N
In all three problems the interaction is repulsive because the force is positive.