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# At what separation should two equal charges 1.0 C be placed so that the force between then equals the weight of a 25 kg person ?

$(a)\;6\times10^4\;m\qquad(b)\;3\times10^4\;m\qquad(c)\;6\times10^3\;m\qquad(d)\;2\times10^4\;m$

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• The SI unit of quantity of electric charge is the coulomb, which is equivalent to about $6.242 \times 10^{18}$ e (e is the charge of a proton). Hence, the charge of an electron is approximately $−1.602 \times 10^{−19}$ C.
Answer : (c) $6\;\times10^3\;m$
Explanation : $\;\large\frac{9\times10^9\times1\times1}{r^2} = 25\times10\quad\;(\large\frac{Rq_{1}q_{2}}{r^2}=mg)$
$r=\large\frac{3}{5}\times10^4=0.6\times10^4\;m\;.$

edited Aug 11, 2014