As shown in the figure, a ball with a mass of $0\mathrm{.}870$ g and positive charge of q$=41\mathrm{.}1\backslash$mu

C is suspended on a string of negligible mass in a uniform electric field.

We observe that the ball hangs at an angle of $\backslash$theta

$=21\mathrm{.}0$o from the vertical. What is the magnitude of the electric field?