Electrostatic force between charges.

[poltry]

Hi! we did a lab where we charged a big sphere with 5kV, with this sphere we then charged another smaller sphere that was hanging loose from a string by touching it. We had to measure the distance the small sphere moved from its initial position and also the distance from the big sphere to the final position of the small sphere. We did this about 5-6 times, and my task is to find the relationship between force and separation. i read that the force is proportional to square inverse of the separation. how would i show this on a graph? the separation is the distance from the initial to the final position of the small sphere? and what is the force? the 5kV? or what? help needed thanks

 

[member 553083]

The force is the electrostatic force between the two spheres, which is proportional to the inverse square of the separation. You can show this on a graph by plotting the separation (distance from the initial to the final position of the small sphere) on the x-axis, and the electrostatic force on the y-axis. The relationship should be a straight line, with an inverse square dependence.