Best answer

V_{2}/V_{1} = N_{2}/N_{1} = K

If the number of turns of secondary winding (i.e. N_{2}) is more than number of turns of primary winding (i.e. N_{1}) then voltage on secondary winding (i.e. V_{2}) will be more than the voltage on primary winding (i.e. V_{1}) and if the voltage on secondary side is more than primary side then the transformer is known as **step up transformer.**

If the number of turns of secondary winding (i.e. N_{2}) is less than number of turns of primary winding (i.e. N_{1}) then voltage on secondary winding (i.e. V_{2}) will be less than the voltage on primary winding (i.e. V_{1}) and if the voltage on secondary side is less than primary side then the transformer is known as **step down transformer.**

If the number of turns of secondary winding (i.e. N_{2}) is equal to number of turns of primary winding (i.e. N_{1}) then voltage on secondary winding (i.e. V_{2}) will be equal to the voltage on primary winding (i.e. V_{1}) and if the voltage on secondary side is equal to primary side then the transformer is known as **isolation transformer.**

The ratio of current on primary winding of transformer (i.e. I_{1}) to current on secondary winding of transformer (i.e. I_{2}) is called as current ratio of transformer.

V_{2}/V_{1} = I_{1}/I_{2} = K

The ratio of number of turns of secondary (i.e. N_{2}) to number of turns of primary (i.e. N_{1}) is called as transformation ratio of transformer. It is denoted by K.

K = N_{2}/N_{1}