Magnetic material behavior under cyclic magnetization What is the name of the phenomenon in which the magnetization of a material lags behind the applied magnetizing force when cycled, producing a characteristic loop on the B–H curve?

Introduction / Context:
When ferromagnetic materials are driven through cycles of magnetization, the relationship between magnetic flux density (B) and magnetizing force (H) does not follow a single line. Instead, a loop forms because the material’s response lags the excitation. This phenomenon is called hysteresis and is central to core-loss analysis in transformers and inductors.

Given Data / Assumptions:

• Cyclic magnetization of a ferromagnetic core.
• Observation of a closed loop in the B–H plane.
• Steady temperature and frequency for qualitative description.

Concept / Approach:
Hysteresis arises due to domain wall motion and irreversible processes at the microscopic level. As H increases and decreases, domains reorient with energy loss, so the path on the B–H plot during increasing H differs from the path during decreasing H. The area of the loop equals energy dissipated per cycle per unit volume, contributing to core heating and efficiency limits.

Step-by-Step Solution:
Apply increasing H: B rises toward saturation.Reduce H to zero: B does not return to zero, leaving remanence (Br).Reverse H: coercive field (Hc) needed to reduce B to zero.Complete cycle: loop encloses an area equal to hysteresis energy loss per cycle.

Verification / Alternative check:
Compare materials: soft magnetic cores (silicon steel, ferrites) have narrow loops (low loss), while hard magnetic materials (permanent magnets) have wide loops with high coercivity and retentivity.

Why Other Options Are Wrong:
Induction: general term for EMF generation, not lag behavior.Retentivity: the residual magnetization Br after removing H, a feature within hysteresis but not the lag itself.Reluctance: opposition to magnetic flux, a circuit parameter, not a cyclic lag effect.

Common Pitfalls:
Confusing coercivity, remanence, and hysteresis; remember: the loop is hysteresis, its width relates to coercivity, and the intercept at H=0 is remanence.

Final Answer:
Hysteresis