Which material is used to make electromagnets and why?

Explanation

**Step-by-Step Solution:**

1. **Understanding Electromagnets**: An electromagnet is created when an electric current passes through a coil of wire, generating a magnetic field. The strength of this magnetic field can be enhanced by using a core material.

2. **Choosing the Right Material**: The ideal material for making electromagnets should have specific magnetic properties. It should have low retentivity and low coercivity.

3. **Defining Low Retentivity**: Low retentivity means that when the external magnetic field is removed, the material should not retain significant magnetization. This is important because we want the material to return to its original state (non-magnetized) once the current is turned off.

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