A reasonable upper limit on the amount of charge that can be safely applied to a person is 1 micro Coloumb. What charge density must be applied to the floor to float a person with mass 50 kg and charge 1 micro Coloumb? Model the floor as an infinite plane with uniform surface charge density.
Let the surface charge density be sigma coulomb/m^2
Therefore, Electric field E = sigma/epsilon
where, epsilon = ...
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