Question

The magnitude of electrostatic constant in air, in $N{m}^2/C^2$ is :

• A. $9\times {10}^5$
• B. $9\times {10}^{11}$
• C. $9\times {10}^9$
• D. none of these

Answer 1

The correct option is C $9\times {10}^9$

The electrostatic constant in air is given by, $k=\frac{1}{4\pi {ϵ}_0}$

$=\frac{1}{4\pi \times (8.854\times {10}^{-12})}$

$=9\times {10}^{9}N{m}^2/C^2$