A) What must the charge (sign and magnitude) of a particle of mass 1.42g be for it to remain stationary when placed in a downward-directed electric field of magnitude 610N/C ? Use 9.81m/s^2 for the magnitude of the acceleration due to gravity.
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^-27kg for the mass of a proton, 1.60×10^-19C for the magnitude of the charge on an electron, and 9.81m/s^2 for the magnitude of the acceleration due to gravity.