$($a$)$ A $0\mathrm{.}750$ m long section of cable carrying current to a car starter motor makes an angle of $60$ with the Earth$$s magnetic field $(5\mathrm{.}00105).$ What is the current when the wire experiences a force of $7\mathrm{.}00103?$

$($b$)$ If you run the wire between the poles of a strong horseshoe magnet, subjecting $5\mathrm{.}00$ cm if it to a $1\mathrm{.}75$ T field, what force is exerted on the wire?