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ANS:C - soft iron

Soft iron refers to a specific type of iron that possesses certain characteristics making it suitable for various applications, particularly in magnetic circuits and electromagnetism. Here's an explanation of soft iron:

1. Material Properties: Soft iron is characterized by its relatively high magnetic permeability and low coercivity. This means that it can be easily magnetized and demagnetized when exposed to an external magnetic field. Soft iron has a low residual magnetism, which allows it to quickly lose its magnetization once the external field is removed.
2. Magnetic Applications: Soft iron is commonly used in magnetic circuits and devices where temporary magnetization is desired, such as electromagnets, relays, transformers, and magnetic shielding. Its high magnetic permeability allows it to concentrate magnetic flux lines efficiently, making it ideal for enhancing the magnetic field strength in these applications.
3. Low Coercivity: Soft iron's low coercivity means that it requires relatively low levels of magnetic field strength to magnetize it. This property makes soft iron well-suited for applications where rapid magnetization and demagnetization are important, such as in alternating current (AC) electrical systems.
4. Mechanical Properties: In addition to its magnetic properties, soft iron typically exhibits good mechanical properties, including ductility and malleability, which allow it to be easily formed, bent, or machined into various shapes and configurations.
5. Usage Considerations: Despite its favorable magnetic and mechanical properties, soft iron is susceptible to corrosion and oxidation. Therefore, it is often coated or plated with protective materials such as nickel or zinc to improve its durability and resistance to environmental degradation.

Overall, soft iron is a versatile material valued for its magnetic properties, making it essential in numerous applications where temporary magnetization and efficient magnetic flux control are required, particularly in electrical and electromechanical systems.