# please expain permitivity in coulombs law? what does ‘k’ stand for in this equation?

Aarti Gupta
9 years ago
Electrostatic phenomena arise from the forces that electric charges exert on each other.Such forces are described by Coulomb's law according to which the electric force between two stationary charged particles--
1).is inversely proportional to the square of the separation r between them and directed along the line joining them;
2).is proportional to the product of the charges q1 and q2 on the two particles.Force
is attractive if the charges are of opposite sign and repulsive if the charges have the same sign.Thus,we can express Coulomb’s law as an equation as--
F = k q1 * q2 / r2
where k is a constant called the Coulomb constant whose value depends on the choice of units.The SI unit of charge is the coulomb (C).k in SI units has the value 8.9875 * 109Nm2/C2
This constant is also written as--
k = 1/ 40
where,0 is known as the permittivity of free space and has the value
8.854 2 × 10 –12 C2/N.m2.