1. A rod of length L carries a uniform linear charge density A. Find the potential at a distance d from an end of the rod (a) measured along the

same line as the rod, (b) measured perpendicular to the rod. \int \frac{d x}{\sqrt{a^{2}+x^{2}}}=\ln \left(x+\sqrt{a^{2}+x^{2}}\right)