Question

How far apart the two electrons be If the force between them equals the weight of an electron.

Answer 1

Mass of electron, $m=9.1\times {10}^{-31}$

Weight of electron, $W=mg$

$=9.1\times {10}^{-31}\times 10$

$=9.1\times {10}^{-30}N$

Given,

$mg=\frac{1}{4\pi {ϵ}_0}\frac{q^2}{r^2}$

$9.1\times {10}^{-30}=\frac{9\times {10}^9\times {(1.6\times {10}^{-19})}^2}{r^2}$

$\Rightarrow$ $r^2=\frac{9\times {10}^9\times 2.50\times {10}^{-38}}{9.1\times {10}^{-30}}$

$=2.53\times 10$

$r^2=25.3$

$r=\sqrt{25.3}$

$r\approx 5m$