1. The problem statement, all variables and given/known data Using Gauss' law, or otherwise, find an expression for electric potential at a distance r from an infinitely long straight line of charge of length h with linear charge density lambda per unit length. 2. Relevant equations q=lambda*h 3. The attempt at a solution The first part is easy, using gauss' law to find electric field..the result i get is E=lambda/(2*pi*r*epsilon_0) ..which should be correct. But then i'm not sure how to find potential in this case. I tried using the equation: E= - grad*V so V = integral[E*dl] V= -lambda/(2*pi*epsilon_0) integral_from_infinity_to_r[(1/r) dr] ..which leads me to: V = -lambda/(2*pi*epsilon_0) [ln(r)] where the ln(r) is evaluated from infinity to r...and im not sure that looks right, or where to go from there.. I don't know what the solution is supposed to be and I couldn't find any explanations when i googled it..anyone have any idea??? :uhh: thankyou sooo much!!!!