As shown in the figure above, a ball with a mass of 0.180 g and positive charge of q=36.0 μC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of θ=18.0o from the vertical. What is the magnitude of the electric field?

F=Mass*Gravity

Convert to Coulombs first.

Find the force of gravity on the object (Y

direction),F=Mass*Gravity. Then determine the x component of

using Force of gravity*TAN(Angle Given)

Divide by Coulombs.

based on those thoughts, I get .18*9.81 = 1.76580

next i take 1.77 * tan(18) = .57374

then i divided .57511/36E-6 = 15937.311

but its not the right answer =\