I have 3 problems I'm stuck on for homework: 1) The force of repulsion that two like charges exert on each other is 4.3 N. What will the force be if the distance between the charges is increased to 9 times its original value? Not sure what equation to use here to solve this one... 2) Two tiny conducting spheres are identical and carry charges of -20.1 C and +38.8 C. They are separated by a distance of 1.96 cm. (a) What is the magnitude of the force that each sphere experiences? (b) The spheres are brought into contact and then separated to a distance of 1.96 cm. Determine the magnitude of the force that each sphere now experiences. What equation should I use here? The one I'm using below? 3) A charge of -3.06 C is fixed at the center of a compass. Two additional charges are fixed on the circle of the compass (radius = 0.134 m). The charges on the circle are -3.02 C at the position due north and +6.29 C at the position due east. What is (a) the magnitude and (b) direction of the net electrostatic force acting on the charge at the center? Specify the direction as an angle relative to due east. For part A I used the equation Fe=Kq1q2/r^2 Fe=-3.06*10^9*(-3.02*10^-6)*(6.29*10^-6)=.058127148/(.134)^2=3.237199153 I know this is wrong, can anyone help me find my problem?