How much will be the current?

If i use a transformer of 2A to make a 12v dc power supply, what will be the output current? Will it be same or some variance will come?

A transformer is not rated in Amps, it has to be rated in volts as well.

So right You are. They declare it in VA. It's the power it can provide

and that would be Watts. That AC voltage from the secundary winding needs to be rectified, if You wanna use it for DC applications, and therefore You need to make calculation of trnsforming ACV to DCV thus giving You a idle state of a transformer giving You about 1,5 times of the reading of Yout meter.... e.g. Your transformer says its out put is 12Volts, but if You rectify the input it can easyely show 18VDC

BUT, if You put a load on that, exceeding the VA, it will drop rapidally to 12V, but still maintain the VA spesification

That said

rickharris22 days ago

It depends on the load. Electrical items DRAW current from the source. If your pow3er supply is capable of providing 2 amps then that is the maximum you can draw, but how much depends on the load. (or on other electronic limiting factors you may build into the power supply e.g. current limiting circuits)

+1