posted by Rachel .
A small m = 2.00 g plastic ball is suspended by a L = 24.0 cm long string in a uniform electric field, as shown in Figure P15.50. If the ball is in equilibrium when the string makes a 18.0° angle with the vertical as indicated, what is the net charge on the ball?
To slove as listed, you need to know the charge of the Electric Field:
since cos/sin= tan
q= mg tan(18)/E