Please help with electrostatic force physic problem!!!?

Question

Honeybees actively foraging in the field have been found to be electrically charged, due largely to air resistance as they fly. The charges carried by a bee, which can be as great as 95 pC, is thought to play a significant role in pollination -- the bee can detach grains of pollen from a distance, like a charged comb attracting bits of paper. Given the force required to detach pollen from an avocado stigma is 3.5 multiplied by 10-10 N, find the maximum distance at which the electrostatic force between a bee and a grain of pollen is sufficient to detach the pollen. Treat the bee and pollen as point charges, and assume that the pollen has a charge opposite in sign and equal in magnitude to the bee.

Answer 1

The magnitude of the electrostatic force is given by Coulomb's law:

F = (1/(4∙π∙ε₀))∙q₁∙q₂/r²

Because the two charges are identical

F = (1/(4∙π∙ε₀))∙q²/r²

This Force need to exceed a minimum  force to detach the pollen.shall exceed a minimum lift force:

F ≥ Fmin

Hence:

(1/(4∙π∙ε₀))∙q²/r² ≥ F_min

<=>

r ≤ q / √ (4∙π∙ε₀∙F_min)

<=>

r ≤ 95×10⁻¹²C / √( 4∙π ∙ 8.854×10⁻¹²C²/Nm ∙ 3.5×10⁻¹⁰N )

<=>

r ≤ 0.4814m