Why Transformer core is laminated instead of solid?

What is laminated core?

In some Electrical machines likes transformers or motors, its core is made of ferro-magnetic alloy which is made into thin sheets. It gets varnished or oxidized to get high resistance. After that it is clamped together to form a core block. 

LAMINATED TRANSFORMER CORE

Process

Transformer core is the part which provides the low reluctance path to magnetic flux leakage from primary winding to the secondary winding. 

Due to the alternating supply in the winding which is wounded on the core, the alternating magnetic field induce current in the core.  The direction of current cause change in magnetic field which flows in direction opposite to actual magnetic flux. It will cause loss in it.

The induced current is in the shape of eddies or whirlpool inside the material. this is not necessary for this process. So that we call it as loss. Due to the current in the form of eddy. It is called as eddy current loss.

By providing resistive path to it, it can be reduced. Instead of using a core as solid conductive material, we can use laminated core. Due to the air gap between each sheet, the loss of the current will be reduced.

Eddy Current

According to the faradays law of induction, When a conductor is placed in the changing magnetic field, the induced current in the conductor is termed as eddy current. Eddy Currents flow in closed loop within conductors, in planes perpendicular to the magnetic field.