The mass of the ball is 40 milligrams, the applied potential difference is 480 V and the plate separation is 6 cm. If the string hangs at an angle of 20deg to the vertical, determine the charge on the pith ball.
E = V / d
E = F / q
The Attempt at a Solution
I figured first i should use E = v/d so i did
E = 480/0.06 = 8000
Then i found F using trig and vectors
Cos20 = (40*10^-6) / F
Thus F = 4.26*10^-4 N
Then i plugged in my F and E into the equation q = F / E
q = 4.26*10^-4 N / 8000 = 5.3*10^-9 C
Which is 5.3 nC
But the correct answer is supposed to be 18nC
Forever grateful for assistance.