What are the fixed values in transformer?
It appears that you misunderstand how a transformer works. It is true that the secondary voltage and current are a function of the primary voltage and current.  However, the primary current depends on the primary voltage and the load that the transformer represents.  In an ideal transformer, the secondary load reflects back to the primary divided by the square of the turns ratio.  If you place an infinite resistance across the secondary (i.e. an open circuit), then the primary voltage will also see an open circuit (infinity divided by \$N^2\$).  Therefore there will be no primary current and hence, no secondary current. Hence there is no power transferred by the transformer.  

If you place a finite resistance across the secondary, say R, then that will be reflected back to the primary as \$ \frac {R}{N^2} \$ which is finite. The primary current, per Ohm's law, will be the primary voltage divided by this resistance.  The secondary current will be the primary current divided by N, and the secondary voltage will be the primary voltage multiplied by \$ N \$. All of the power from the primary voltage will be transferred to the secondary since an ideal transformer is 100% efficient.  However Ohm's is satisfied by both the primary and secondary circuits.