By rubbing with a magnet, a number of times in the same direction ______ can be converted into a magnet.

Options

A. Cork piece
B. Glass rod
C. Iron bar
D. Any material

Explanation

To solve the question "By rubbing with a magnet, a number of times in the same direction ______ can be converted into a magnet," we need to identify which material can be magnetized through this process.

### Step-by-Step Solution:

1. **Understanding the Process of Magnetization**:
- Magnetization occurs when a magnetic field aligns the magnetic domains of a material. Rubbing a magnet on a material in the same direction helps align these domains.

2. **Identifying Magnetic Materials**:
- Not all materials can be magnetized. Only certain materials, known as magnetic materials, can be turned into magnets. Common examples of magnetic materials include iron, nickel, and cobalt.

3. **Evaluating the Options**:
- The options provided are:
- Cork piece
- Glass rod
- Iron bar
- Any material

4. **Analyzing Each Option**:
- **Cork piece**: This is not a magnetic material; it cannot be magnetized.
- **Glass rod**: This is also not a magnetic material; it cannot be magnetized.
- **Iron bar**: This is a magnetic material. When rubbed with a magnet in the same direction, it can be magnetized.
- **Any material**: This is incorrect because not all materials can be magnetized.

5. **Conclusion**:
- The only option that can be converted into a magnet by rubbing with a magnet in the same direction is the **iron bar**.

### Final Answer:
By rubbing with a magnet a number of times in the same direction, **iron bar** can be converted into a magnet.

---