Question

State why soft iron is preferred to steel as a material for the core of a transformer.

Answer 1

Soft iron is preferred over steel primarily because it has lower hysteresis loss and higher magnetic permeability:

• Low Hysteresis Loss: The magnetic field in a transformer core reverses 100 times per second (at 50 Hz). Soft iron dissipates much less energy as heat during these cycles compared to steel, making the transformer more efficient.
• High Permeability: Soft iron is easily magnetized and demagnetized. This ensures that the magnetic flux is easily conducted from the primary to the secondary coil with minimal leakage.
• Low Retentivity: Unlike steel, soft iron does not stay strongly magnetized once the current stops. This “soft” magnetic behavior is essential for the rapid switching required in AC circuits.