A pollen particle, treated as a point object, possesses a ma…

A pollen particle, treated as a point object, possesses a mass of 0.3 kg and is situated within a uniform electric field of 0.2 N/C directed vertically upward. The pollen particle experiences an upward acceleration of 15 m/s². Given the gravitational acceleration of g = 9.8 m/s², what is the charge Q on the pollen particle (unit in C)?

A +5×10-9 C point-charge is in static equilibrium at the cen…

A +5×10-9 C point-charge is in static equilibrium at the center of a conducting spherical shell, which has an inner radius of 0.3 m and an outer radius of 0.5 m. The shell itself carries a net charge of -6×10-9 C. What is the magnitude of the electric field immediately outside the outer surface of the shell, with unit in N/C? Note that magnitude is positive.