Transformer works on the principle of mutual induction of two coils or Faraday Law’s Of Electromagnetic induction. When current in the primary coil is changed the flux linked to the secondary coil also changes. Consequently an EMF is induced in the secondary coil due to Faraday law’s of electromagnetic induction.
The operation of transformer mainly works on the principle of mutual inductance between two circuits linked by a common magnetic flux. A transformer is basically used for transformation of electrical energy. When flux linked with primary coil changed the flux linked with secondary coil also changes. Hence EMF induced in the secondary coil.