College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 47

It is desired to construct a solenoid that will have a resistance of 5.00 (at 20°C) and produce a magnetic field of 4.00 × 10 2 T at its center when it carries a current of 4.00 A. The solenoid is to be constructed from copper wire having a diameter of 0.500 mm. If the radius of the solenoid is to be 1.00 cm, determine (a) the number of turns of wire needed and (b) the length the solenoid should have.