We know that,

Electrostatic force,

Where

Є_o is the permittivity of vacuum

q₁, q₂ is the magnitude of the charges on the charge particles

r is the distance between the two charge particles.

Taking the dimensions,

Note that Charge = Current × Time. Hence, its dimensional formula is

Note that 4π is a dimensionless constant. Note that . Hence, . Also, r is just distance or length. Thus,

Rearranging, we get