1. The problem statement, all variables and given/known data Two parallel plates with opposite charges are 0.01 m apart and have a potential difference of 100 V. A charged spherical object has 20 excess electrons stays motionless between the plates. If the density of the object is 1000 kg/m^3, what is the radius of the spherical object? 2. Relevant equations E=V/d Fq=qE Fg=mg density=m/Vs Vs = 4/3 pi r^3 3. The attempt at a solution I equated the electric force and the gravitational force as they are equal. E = 100/0.01=10000 vollts/m Therefore, Fq = 20 x 1.602x10^-19 x 10000 = 3.204x10^-14 Fg=m x 9.81 (I am assuming that I don't need to use the universal law of gravity because I don't know how high the apparatus is off the ground). Therefore, Fg=Fq => m x 9.81 = 3.204x10^-14 => m = 3.27 x 10^-15 kg density = m/Vs => Vs = m/density = 3.27 x 10^-18 Vs = 4/3 pi r^3 => r = 0.92x10^-6 meters or 0.92 micro meters. However, this answer is wrong. Where have I gone wrong? Thank you for helping.