What is the core of a transformer made of?

The core of a transformer is made up of soft iron because of its unique magnetic properties that make it perfectly suited for this application. Soft iron has high magnetic permeability, meaning it can be magnetised and demagnetised very easily and rapidly with each alternating current cycle. This is absolutely essential in a transformer because the magnetic field inside the core reverses direction thousands of times per second. Additionally, soft iron has low magnetic retentivity, meaning it does not retain magnetism after the magnetising field is removed — preventing energy loss and heat buildup inside the core.

• High Permeability: Soft iron allows magnetic flux to pass through it very easily, making the transformer highly efficient
• Low Retentivity: Loses magnetism instantly when current changes direction — essential for efficient AC operation with minimum energy loss
• Laminated Core: Soft iron core is made in thin laminated sheets to reduce eddy current losses, further improving transformer efficiency
• Why Not Steel: Steel has high retentivity — it retains magnetism too long, causing excessive energy loss as heat in AC applications
• Why Not Copper/Aluminium: These are non-magnetic materials — completely unsuitable for transformer cores which require strong magnetic flux conduction