# The voltage of primary and secondary coil of transformer is same?And current is same or not?

What will remain constant (assuming 100% efficiency) is the power on both sides, and power is the product of current and voltage (I.e. $P = I \times V$) so if the voltage rises (a step-up transformer) current must fall and vice versa.
The most useful equation (again assuming it is efficient) is the ideal transformer equation: ${N}_{1} / {N}_{2} = {V}_{1} / {V}_{2}$ and the currents follow as a result to keep power constant.