Question

Two identical conducting spheres with negligible volume have $2.1\text{nC}$ and $-0.1\text{nC}$ charges, respectively. They are brought into contact and then separated by a distance of $0.5\text{m}$. The electrostatic force acting between the spheres is _______$\times {10}^{-9}\text{N}$.

[Given : $4\pi {ϵ}_0=\frac{1}{9\times {10}^9}$ in SI unit]

Answer 1

When they are brought into contact& then separated by a distance $=0.5\text{m}$
Then charge distribution will be
The electrostatic force b/w the spheres is
$F_e=\frac{k{q}_1{q}_2}{r^2}$
$F_e=\frac{9\times {10}^9\times 1\times {10}^{-9}}{{0.5}^2}$
$F_e=\frac{900}{25}\times {10}^{-9}$
$F_e=36\times {10}^{-9}\text{N}$