a Consider an infinite wire with current $I_2$ and

an arc in the shape of a semicircle $($center $0)$

with current $I_1$ as shown in the figure below. If

$I_1>I_2$ and $R_1>R_2.$ What is the direction of the

magnetic feld at point $O.$

$+z$

$-z$

The magnetic field is zero

The given is not sufficient

None of the above

$b$

Consider an infinite wire with current $I_2$ and an arc

in the shape of a semicircle $($center $0)$ with current

$I_1$ as shown in the figure below. If $I_1=0\mathrm{.}2I_2$ and $R_1=$

$R_2.$ What is the direction of the magnetic neld at

point $0.$

The magnetic field is zero

The given is not sufficient

None of the above

need all explanation $($ mathematical $-$ equations$)$

as much you can please