1. A uniform electric field E=100000 N/C causes the 5.0 g ball to hang at a 450 angle. What is the charge on the ball?
2. What is the magnitude of electric field at point P due to a nonconducting infinite planes of negative charge with uniform charge density s = -9µC/m2 and point charge Q = +10µC placed at point Q. The distance between points P and Q is 0.5 m. Line, connecting points Q and P, is parallel to the planes.