For substance hysteresis `(B-H)` curve are as shown in figure. For making temporary magnet which of the following is the best?

Options

A.
B.
C.
D.

Explanation

To determine which substance is best for making a temporary magnet based on the hysteresis (B-H) curve, we can follow these steps:

### Step 1: Understand the Hysteresis Curve
The hysteresis curve (B-H curve) represents the relationship between magnetic flux density (B) and magnetic field strength (H) for a given material. The shape of this curve provides insights into the magnetic properties of the material.

### Step 2: Identify Characteristics of Temporary Magnets
Temporary magnets are materials that can be magnetized easily but lose their magnetism quickly when the external magnetic field is removed. Therefore, the hysteresis loop for a temporary magnet should be:
- Long: This indicates that the material can be magnetized to a high level.
- Narrow: This suggests that the material will demagnetize quickly after the external field is removed.

### Step 3: Analyze the Given Options
We need to analyze the provided options based on the characteristics of the hysteresis curves:
- **Option A**: The curve is long but not narrow.
- **Option B**: The curve is long but not narrow.
- **Option C**: The curve is narrow but not long.
- **Option D**: The curve is both long and narrow.

### Step 4: Determine the Best Option
From the analysis:
- Options A and B are long but not narrow, which is not ideal for temporary magnets.
- Option C is narrow but not long, which also does not meet the criteria.
- Option D is both long and narrow, making it the best choice for a temporary magnet.

### Conclusion
Thus, the best option for making a temporary magnet, based on the hysteresis curve characteristics, is **Option D**.

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