Which of the following materials has got the maximum retentvity ?

Options

A. Copper
B. Zinc
C. Soft iron
D. Hard iron

Answer

To determine which material has the maximum retentivity, we will analyze the properties of the given materials: copper, zinc, soft iron, and hard iron.

### Step-by-Step Solution:

1. **Understanding Retentivity**:
- Retentivity is defined as the ability of a material to retain magnetization after the external magnetic field is removed. It is a measure of how well a material can hold onto its magnetic properties.

2. **Analyzing the Options**:
- **Option A: Copper**: Copper is a non-magnetic material. It does not retain any magnetic properties after the external magnetic field is removed. Therefore, it has low retentivity.
- **Option B: Zinc**: Zinc is also a non-magnetic material. Like copper, it does not retain magnetism after the removal of an external magnetic field, resulting in low retentivity.
- **Option C: Soft Iron**: Soft iron is known for its high magnetic permeability but low retentivity. It can easily become magnetized but loses its magnetism quickly once the external field is removed.
- **Option D: Hard Iron**: Hard iron, on the other hand, is known for its high retentivity. It retains its magnetization for a longer period after the external magnetic field is removed.

3. **Conclusion**:
- Among the given options, hard iron has the maximum retentivity. Therefore, the correct answer is **Option D: Hard Iron**.