The efficiency of transformer decreases due to following reason :
(i) Flux loss :The coupling of the primary and secondary coil is never perfect and whole of the magnetic flux produced in primary coil never gets linked up with the secondary coil.
(ii) Copper loss: Due to to resistance of the winding of primary and secondary coil some electrical energy is always converted into heat energy.
(iii) Iron loss:The varying magnetic field produces eddy current in the iron case which leads to the wastage a energy in the form of heat. It is minimised by using a laminated from core.
