http://img136.imageshack.us/img136/7548/44938265by3.jpg [Broken] Okay I am not sure how to do this problem without having lambda. I talked to my professor and he said I don't need lambda. I know that finding the potential due to a continuous charge is dV = (Kdq)/r But in this case, I am not sure how to do it. What is dq? Can someone please explain to me how do I approach doing this problem.