Log1989 task no. 16.30

The winding of the coil, whose diameter is d = 10 cm, consists of tightly adjacent turns of a thin wire. Determine the minimum length Lmin of the coil, at which the magnetic induction at its center differs from the magnetic induction of the field of an infinitely long solenoid containing the same number of turns per unit length, by no more than 0.5%. The current passing through the winding is the same in both cases.