If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as___________________?
A. Kelvin’s law
B. Ohm’s law
C. Kirchhoffs law
D. Faraday’s law
E. none of the above