The transformer is connected by mutual induction of two circuits or coils under the same magnetic flux. The two inductive coils are magnetically connected to a uniform laminated core without electrical connection between the two. As the alternating voltage is applied to one of the coils, the variable current generates a variable magnetic force line in that coil , which flows through the core and intersects with the adjacent coil. As a result , mutual voltage is captured in the coil according to Faraday's principle of electromagnetic induction. This induced voltage is the transformer-voltage and the process of producing this voltage is called transformer action. When the circuit is completed by connecting the lead to the second coil, current will flow in it.