Question

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

Answer 1

Generally both voltage and current will change from primary to secondary coils.

Explanation:

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 = IxxV`) 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.