To get the ideal result of voltage transformation ratio, both primary and secondary voltages have to be taken in a ratio format. Since this is a voltage transformation that is to be considered in this process; it is of utmost importance that a number of windings is to be measured.
It is this number of turns in a secondary winding that is to be placed against a number of turns that is to be faced in a primary winding that is constituted as voltage transformation ratio.
When N2 is less than N1 and K is less than 1, it is condition of a step-down transformer.
When N2 is greater than N1 and K is greater than 1, it is condition of a step up transformer.