Question

A long, straight wire of length 2L on the y-axis carries a current I. According to the Biot-Savart Law, the magnitude of the magnetic field due to the current at a point (a,0) is given by

B(a)= (mu sub 0 multiply by I) divided by 4pi times the integral from -L to L of (Sine beta / r^2)dy

where mu sub 0 is a physical constant, a>0, and beta, r, and y are related.

a)Show that the magnitude of the magnetic field at (a,0) is
B(a)= (mu sub 0 times I and L) divided by (2pi*a*sqrt(a^2 + L^2))

b)what is the magnitude of the magnetic field at (a,0) due to an infinitely long wire
(L -> infinity)?

Note: (*) means multiply by