Homework Statement \r\nDetermine the inductance of a solenoid with 650 turns in a length of 21 cm. The circular cross section of the solenoid has a radius of 4.2 cm.\r\n\r\n\r\nHomework Equations\r\n\r\n???\r\n\r\nThe Attempt at a Solution I've looked all over my textbook and cant come up with a possible equation(s). Help!!!