Consider the figure below.

$($a$)$ Using the symmetry of the arrangement, determine the direction of the force on $q$ in the figure above, given that $q_a=q_b=+9\mathrm{.}00C$ and $q_c=q_d=-9\mathrm{.}00C.$

$($b$)$ Calculate the magnitude of the force in newtons on the charge $q,$ given that the square is $10\mathrm{.}0cm$ on a side and $q=4\mathrm{.}00C.$

$N$

Additional Materials