In this article presents the results of a study on the meaning and significance of the coefficient of proportionality in Coulomb's law of interaction of two point electric charges. As you know the proportionality factor in Coulomb's law in one of its forms is the product of the square of the speed of light by a constant factor k*c^2. It is not clear why nature had to choose the constant factor for his law. This is a factor k=10^(-7). There is no rational explanation for this value. It seems quite logical to include this factor into the value of the electric charge. This will require a redefinition of the corresponding value of the electric charge. The numerical value of the charge is reduced to 10^(3,5) times. The proportionality coefficient is simplified. It will be equal to the square of the speed of light c^2. He ceases to be a far-fetching. In this case the physical quantity electrical charge will take its natural value. This change will require adjustment system Planck units. The author proposes a refined system of Planck units.