Which of the following is correct for permittivity of free space?

$8.854\times10^{-12}\,C^2N^{-1}m^{-2}$

$8.854\times10^{-12}\,C^2N^{-1}m^{-1}$

$8.854\times10^{-11}\,C^2N^{-2}m^{-2}$

$8.854\times10^{-12}\,C^2N^{-1}m^{-2}$

Which of the following is not properties of filed lines?

Two field lines can cross each other.

Field lines start from positive charges and end at negative charges.

Electric field lines do not form any closed loops.

In a charge-free region, electric filed lines can be taken to be continuous curve without any breaks.

Two field lines can cross each other.

$8.854\times10^{-12}\,C^2N^{-1}m^{-2}$

Two field lines can cross each other.

For (r >> a), the field of an electric dipole on the axis is proportional to distance.

The ratio of electric force and gravitational force between a proton and an electron is:

The Electric field due to thin infinitely long straight wire of uniform charged wire will be: