The core of a transformer is typically made of which material?

• A. Copper
• B. Iron
• C. Aluminum
• D. Plastic

Answer: (B)

Transformer cores need a material that guides magnetic flux efficiently and minimizes losses. Iron fits this role because it’s ferromagnetic with high magnetic permeability, so it concentrates the magnetic field and enables efficient energy transfer. In power transformers, the core is typically made of laminated iron (silicon steel) to further reduce eddy-current losses—thin insulating layers between sheets interrupt circulating currents and keep losses down. Copper or aluminum are great for windings due to their conductivity, but they don’t provide the needed magnetic path, so they aren’t used for the core. Plastic is non-magnetic and poor at guiding magnetic flux, so it’s not suitable either.