Abstract
In the literature, a widely spread equation to correlate between the optical (sigma(optic)) and electrical (sigma(elec)) conductivities in the form of (sigma(elec) = 2 lambda sigma(opt)/alpha). Unfortunately, the two sides of this equation have different dimensions; i.e. this equation is incorrect and the work by this equation must be stopped. Also, there is another equation suggested by Shankar and Joseph to correlate the electrical conductivity (sigma(e)) with the refractive index (n dimensionless), extinction- (k dimensionless) and absorption coefficient (alpha in m(-1)) in the form of sigma(e) = 2knc/alpha where c is the velocity of light and has m/s units. Unfortunately, the dimensions of the two sides of this equation are not the same and the work by this equation must also be stopped.