What must the charge (sign and magnitude) of a particle of mass 1.47 g be for it to remain stationary when placed in a downward-directed electric field of magnitude 680 n/c ? use 9.81 m/ s 2 for the magnitude of the acceleration due to gravity. view available hint(s) nothing c c submit part b what is the magnitude of an electric field in which the electric force on a proton is equal in magnitude to its weight? use 1.67×10−27 kg for the mass of a proton, 1.60×10−19 c for the magnitude of the charge on an electron, and 9.81 m/ s 2 for the magnitude of the acceleration due to gravity. view available hint(s) nothing n/c n / c submit provide feedback next