What is the strength of an electric field that will balance the weight of a proton?
First of all, work out the force due to gravity on your proton or electron. The recall that the electric force is given by the electric field strength multiplied by the charge of the particle. Equate the two forces – mg = qE Solve for E. For the xenon bit: The distance from the proton to the core of the atom is 4fm + the 6fm of radius = 10fm. The charge on the atom is 54e, so the electric field is given by E = 54e / (4pi e0 * (10fm)^2). Then work out the force on the proton, formula as above, and divide by the mass of the proton to get its acceleration.
