$\frac{1}{4 \pi \epsilon}$ এর মান কত?

$9 \times 10^{-9} \mathrm{Nm}^{2} \mathrm{C}^{-2}$

$10 \times 10^{9} \mathrm{Nm}^{2} \mathrm{C}^{-2}$

$9 \times 10^{9} \mathrm{Nm}^{2} \mathrm{C}^{-2}$

$8 \times 10^{9} \mathrm{Nm}^{2} \mathrm{C}^{-2}$