1. Two charges are separated to a distance of 100cm causing the electric force between them to decrease by exactly a factor of 5. What is their initial separation distance?

2. Two charges are attracted by a force of 25 N when separated by 20cm. What is the force between the charges when the distance between them is 90cm?

3. Two Charges of -1.0µC are placed at opposite ends of a meter stick. Where on the meter stick cold (a) a free electron and (b) a free proton be placed on the meter stick and be in electrostatic equilibrium?

4. Two charges, q1, and q2, are located at the origin and at (0.50 m, 0), respectively. Where on the x axis must he third charge, q3, of arbitrary sign be placed to be in electrostatic equilibrium if (a) q1 and q2 are like charges of equal magnitude, (b) q1 and q2 are unlike charges of equal magnitude, and (c) q1=+3.0µC and q2=-7.0µC?