Example:The charged line.Find the electric potential as a function of the radial distance R from an infinite charged line of uniform charge density入. λ Solution: E= 2π8，r AU=∫EdI= dr P 入-nr 2π6。 2π6。 Example: The charged line. Find the electric potential as a function of the radial distance R from an infinite charged line of uniform charge density . ra P r Solution: r E   o  2  dr r U E dl o o r r o r r         2   r r r o o r r o o ln 2 ln 2        