A coil made of tightly wound aluminum wire is intended to generate a magnetic field of strength 0.063 T at its center. The length of the coil is 45.0 cm, and its diameter is 2.0 cm. Determine the minimum number of turns per unit length needed if the aluminum wire used is rated to carry a maximum current of 20.0 A. Treat the coil like a solenoid since the length is much greater than the radius.