Question: Why transformer core is laminated?
Answer: Transformer core is laminated to minimize the eddy current.
What is laminated core?
The term laminated core indicates a layered core instead of a single solid core. (See figure below).
Eddy currents are current loops generated by changing magnetic fields. They flow in a perpendicular plane to the magnetic field.
Laminated magnetic core reduces Eddy currents. For this reason, electrically isolated laminations are utilized to manufacture transformers.
The figure below displays side view of transformer core where the Eddy current flow in a solid and laminated core is indicated with red colored lines: