I dont have a single problem, my teachers use this a lot. a few examples, are an uniformely charged circle and a point charge in the middle, where if you move the point charge a small distance perpendicular to the circle, it would begin to oscilate, and i need to find the frequency of oscilation. or, just a couple of point charges on the x-axis at a certain distance to the origin, and you place an oposite charge on the origin and move it a small ammount on the y axis, what would be the frequency of oscilation, or find an expression for the position of the oscilating charge. equations i think would be relevant are electric force and harmonic oscilation: Fe = kqQ/r^2 and F=-Kx Would the answer be just to substitute the forces for eachother and have kqQ/r^2 = -Kx Or do i have to find K for each specific situation? these are "old" problems as in i'm not studying this part of the program anymore, Electric fields and forces are gonna be in the final, and im pretty sure a problem like this is gonna show up. I havent tried to solve the exercises since i dont have the answers i have no idea to check if im correct other than criticizing my results Im sorry i'm not showing any real attempt at solving these, i just need a little push in the right direction on how do i have to think about this?