The core of a transformer is laminated to:

The correct answer is Option (4) → reduce the heating effect due to eddy currents

A changing magnetic flux in a solid iron core induces circulating currents in the core itself, called eddy currents, which waste energy as heat. Making the core from thin laminations insulated from one another breaks up the paths of these currents and greatly increases their resistance, so the eddy currents and the heating they cause become very small.

Why the other options are incorrect

• Option (1) protect it from moisture — Incorrect. The laminations are coated with varnish to insulate them from each other, not to protect the core from moisture.

• Option (2) reduce its noise — Incorrect. Reducing noise is not the purpose of laminating the core.

• Option (3) reduce loss of energy due to hysteresis — Incorrect. Hysteresis loss depends on the core material and is reduced by using soft iron, which has a narrow hysteresis loop; laminating the core does not reduce it.

Note: A similar question was also asked in CUET (UG) 2025 on 13-05-2025 (Slot 1), and in CUET (UG) 2023 on 14-06-2023 (Slot 2).

NCERT (2026-27):
Transformers – “… But in actual transformers, small energy losses do occur due to the following reasons: … (iii) Eddy currents: The alternating magnetic flux induces eddy currents in the iron core and causes heating. The effect is reduced by using a laminated core.”