Q$5.$ Two long, parallel conductors carry electric currents of $I_1=4\mathrm{.}0$A and $I_2=6\mathrm{.}0A,$ both in the direction $+z$ as shown in the figure. The two conductors are in the $x-z$ plan and are separated by $2\mathrm{.}0$ cm $.$

a$)$ Determine $($the magnitude and direction of$)$ the net magnetic field produced by the two currents at a point $M$ midway between them.

b$)$ Determine $($the magnitude and direction of$)$ the magnetic force per unit length experienced by conductor$-2$ due to the magnetic field generated by the current in conductor$-1.$