coll physics II
posted by physdummy .
A small plastic ball of mass 6.10 10^3 kg and charge +0.150 µC is suspended from an insulating thread and hangs between the plates of a capacitor. The ball is in equilibrium, with the thread making an angle of 30.0° with respect to the vertical. The area of each plate is 0.0150 m2. What is the magnitude of the charge on each plate?
Draw the vector diagram. The vertical force on the ball is mg. The horizontal force must then be mg*tan30. That horizontal force must equal electrostatic force Eq where E is the electric field in the capacitor. E=charge/area*epsilon
solve for charge.