Hey everyone, I just wanted to ask these two questions on electric potential that are having me a bit stuck: A thin rod of length 2L is centered on the x axis on a coordinate plane... The rod carries a unif. distr. charge Q. Determine the potential V as a funct of y for the points along the Y axis. My problem with this--- its not an infinite rod!! I understand that since this rod is of specified length, we will have to some tricky math here and end up doing an integral with our limits for the rod (IE -L and L)... but would all this be is essentially the equation one can derive for the same situation for ELECTRIC FIELD, and just multiply by r? (Where r is the dist on the y axis) Another Question is suppose a conducting sphere of diameter d is charged to a certain voltage V relative to V = 0 at r = infinity. How can we find an equation sets up the surface charge density sigma? (Just in general) I appreciate any help thanks.