We are presenting you a very perplexing but interesting problem which you may have probably encountered in electrostatics. We were trying to calculate the potential of an infinite line charge distribution at a general point by first principle method i.e. the usual integration of the potential of the differential charges on the line charge extending from -∞ to +∞ .We got an indeterminate form[ln(∞ )-ln(-∞)]. We realized that the reference for the potential can not be set to infinity as we unknowingly did for the differential charge appearing in the integration which is wrong for infinite charge distributions.However we can not decide how to set the zero of potential at some other point. Please help us... Regards aim1732 and Mayukh Nath.