Which of the following statement related to the hysteresis loop is incorrect?

Options

A. The curve of B against H for a ferromagnetic material is called hysteresis loop
B. The area of B-H curve is a measure of power dissipated per cycle per unit, area of the specimen
C. Coactivity is a measure of the magnetic field required to destroy the residual magnetism of ferromagnetic material
D. The retentively of a speciment is the measure of magnetic field remaining in the speciment when the magnetising field is removed

Answer

To determine which statement related to the hysteresis loop is incorrect, we need to analyze the properties and characteristics of the hysteresis loop in ferromagnetic materials.

### Step-by-Step Solution:

1. **Understand the Hysteresis Loop**: The hysteresis loop is a graphical representation of the relationship between the magnetic field strength (H) and the magnetic flux density (B) of a ferromagnetic material. It shows how the material responds to changes in the magnetic field.

2. **Identify the Statements**: We need to evaluate the statements provided in the question regarding the hysteresis loop. The key points to consider are:
- The area of the B-H curve represents energy loss per cycle.
- The area of the V-H curve (if mentioned) is related to power dissipated per cycle.
- Retentivity and coercivity are properties of the material related to the hysteresis loop.

3. **Evaluate Each Statement**:
- **Statement 1**: The area of the B-H curve represents the energy dissipated per cycle per unit volume of the specimen. This statement is correct.
- **Statement 2**: The area of the V-H curve is a measure of power dissipated per cycle per unit area of the specimen. This statement is incorrect. The area of the B-H curve is what represents energy loss, not the V-H curve.
- **Statement 3**: Retentivity is the measure of the magnetic field required to destroy the residual magnetism of a ferromagnetic material. This statement is correct.

4. **Conclusion**: Based on the evaluation, the incorrect statement is the one that claims the area of the V-H curve is a measure of power dissipated per cycle per unit area of the specimen. The correct interpretation is that the area of the B-H curve represents energy loss per cycle per unit volume.

### Final Answer:
The incorrect statement related to the hysteresis loop is **Statement 2**.

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