The magnitude of a point charge due to which the electric field 30 cm away has the magnitude $2 \mathrm{newton}/\mathrm{coulomb}$ is $a\times {10}^{-11}$ C. The value of a is:

$\left[\left(1/\left(4{\mathrm{\pi \epsilon }}_0\right)\right)=9\times {10}^9{\mathrm{Nm}}^2/{\mathrm{C}}^2\right]$