Which method is used to reduce iron losses in transformer construction?

The method used to reduce iron losses in transformer construction is laminating the iron core. This technique involves making the core out of thin sheets of iron, which are insulated from one another. The primary reason this reduces iron losses is that it limits the eddy currents that can form within the iron. Eddy currents are loops of electrical current that are induced within conductors by a changing magnetic field in the conductor, and they can lead to significant energy losses in the form of heat.

By laminating the core, these sheets are aligned so that the magnetic flux can still pass through effectively while minimizing the area available for these eddy currents to circulate. As a result, the losses associated with these currents are reduced, improving the efficiency of the transformer.

The other methods mentioned have different impacts on transformer design. Using a solid iron core would not address the eddy current losses effectively, as it provides a continuous path for these currents to flow. Increasing the core size could potentially increase the efficiency but may not specifically target the iron losses as laminating does. Using thicker copper wire affects the resistance and current-carrying capacity, but it does not directly relate to minimizing iron losses in the core material.