a. Derive an expression for the magnetic field strength at distance d from the center of a

Question:

a. Derive an expression for the magnetic field strength at distance d from the center of a straight wire of finite length l that carries current I.
b. Determine the field strength at the center of a current carrying square loop having sides of length 2R.
c. Compare your answer to part b to the field at the center of a circular loop of diameter 2R. Do so by computing the ratio B_square/B_circle.