Temporary & Permanent Magnets

Iron As A Temporary Magnet

Iron possesses inherent properties that make it an ideal candidate for temporary magnet applications due to its soft magnetic material characteristics. This means it can be quickly magnetized or demagnetized, even with a relatively weak magnetic field, highlighting its suitability for temporary magnet uses.

  • Magnetization Process: Iron’s ability to be easily magnetized by even weak magnetic fields allows it to serve efficiently in applications requiring temporary magnets. This characteristic is particularly beneficial in scenarios where magnetic properties need to be adjustable or only temporarily employed.
  • Alloying for Enhanced Performance: By alloying iron with other metals such as Nickel (Ni), Copper (Cu), Manganese (Mn), and Silicon (Si), the resultant materials exhibit significantly enhanced magnetic properties. These alloys can form powerful temporary magnets that are pivotal in various industrial and technological applications.
  • Applications in Electromagnets: Iron’s properties make it an excellent material for creating electromagnets. These devices can have their magnetic field switched on and off, and their magnetic strength varied, offering immense utility in a wide array of applications. Once removed from the magnetizing field, electromagnets lose their magnetism, which is a desired feature in many electrical and electronic devices.
  • Magnetic Shielding: Soft, permeable iron is also employed as an effective material for magnetic shielding (often referred to as magnetic keepers). This application is crucial in preventing unwanted magnetic interference and ensuring the proper functioning of sensitive equipment.


Temporary electromagnets made from iron are instrumental in various applications, including industrial sorting systems that separate metals from landfill materials, moving vehicles, circuit breakers, magnetic relays, electric bells, and transformers. These applications demonstrate the versatility and essential nature of temporary magnets in both everyday and specialized technological solutions.

Steel As A Permanent Magnet

Steel, in contrast to iron, exhibits characteristics of a hard magnetic material, making it less susceptible to easy magnetization or demagnetization. This property necessitates the application of a strong magnetic field to induce magnetism, but once magnetized, steel retains its magnetic properties effectively, making it ideal for use in permanent magnets.

  • Retention of Magnetism: The ability of steel to maintain its magnetism after being exposed to a magnetizing field allows it to serve effectively as a permanent magnet. This characteristic is essential for applications where a consistent and long-lasting magnetic field is necessary.
  • Enhancing Magnetic Properties through Alloying: To further improve its magnetic and structural properties, steel is often alloyed with other materials. This process ensures the creation of strong and durable permanent magnets that can withstand the rigors of their intended applications.


Permanent magnets crafted from steel find extensive use in a variety of devices and applications, such as compasses for navigation, magnetic door catches, moving coil galvanometers, direct current (DC) motors, alternating current (AC) generators, loudspeakers, and many other critical applications. The widespread use of permanent magnets underscores their importance in modern technology and daily life.

Note: The theoretical limit for a permanent magnetic field strength is 5 Tesla, showcasing the limitations inherent in permanent magnet designs. In contrast, electromagnets constructed with ordinary wires are capable of producing steady magnetic fields up to 34 Tesla, highlighting the significant potential for creating powerful magnetic fields through electrical means.

Difference Between Magnetic Properties Of Iron & Steel

The difference between magnetic properties of iron and steel can be summarised in the table below:

Magnetic field strength in solenoidStrongWeak

Worked Examples

Example 1: Compare and Contrast

Compare and contrast the ease of magnetization and demagnetization between iron and steel, and explain how these properties influence their applications in technological and industrial fields.

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Iron, being a soft magnetic material, is easily magnetized and demagnetized even by relatively weak magnetic fields. This characteristic makes it ideal for temporary magnet applications, such as in electromagnets, which require the ability to quickly switch their magnetic properties on and off for various applications like electric bells, transformers, and magnetic relays. On the other hand, steel is a hard magnetic material that is difficult to magnetize or demagnetize, requiring a strong magnetic field to alter its magnetic state. Once magnetized, however, steel retains its magnetism effectively, making it suitable for permanent magnets used in devices requiring consistent, long-lasting magnetic fields like compasses, magnetic door catches, and DC motors. The inherent properties of iron and steel dictate their utility across different applications, with iron favored for adjustable or temporary magnetic needs and steel for durable, long-lasting magnetic applications.

Example 2: Application-based Scenario

An engineer is designing a system for separating metallic waste from non-metallic materials in a recycling plant. Would they be more likely to use iron or steel for the magnet, and why? Consider the properties of both materials and the nature of the application.

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The engineer would likely choose iron for the magnet, specifically in the form of an electromagnet. This decision is based on iron’s soft magnetic properties, which allow it to be easily magnetized and demagnetized. For a recycling plant, the ability to switch the magnetic field on and off is crucial for separating metallic waste from non-metallic materials efficiently. Once the metallic waste is attracted and separated, the electromagnet can be turned off to release the material. Iron’s suitability for temporary magnets, as demonstrated in electromagnets, makes it the preferred choice for such applications that require adjustable magnetic properties.

Example 3: Alloying for Enhanced Performance

Discuss how alloying iron with other metals like Nickel (Ni), Copper (Cu), Manganese (Mn), and Silicon (Si) enhances its magnetic properties. Why is this process significant for industrial and technological applications?

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Alloying iron with metals such as Nickel, Copper, Manganese, and Silicon significantly enhances its magnetic properties by improving the material’s strength, durability, and magnetic permeability. These alloys can form powerful temporary magnets that retain the easy magnetization and demagnetization characteristics of iron while exhibiting improved performance. This enhancement is significant for industrial and technological applications because it allows for the creation of more efficient and reliable electromagnets, magnetic relays, and other devices that benefit from temporary magnetic properties. For instance, in electromagnets used in industrial sorting systems, the improved magnetic properties can lead to more effective separation processes, increased operational efficiency, and better overall performance.

Example 4: Theoretical Limitations and Potential

Explain the significance of the theoretical limit for permanent magnetic field strength (5 Tesla) and the capability of electromagnets (up to 34 Tesla) in the context of designing magnetic devices. How does this difference impact the choice between using permanent magnets and electromagnets in technological solutions?

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The theoretical limit for permanent magnetic field strength at 5 Tesla highlights a fundamental limitation in the design and application of permanent magnets, suggesting that they cannot achieve magnetic fields stronger than this threshold. In contrast, electromagnets can produce magnetic fields up to 34 Tesla, offering a significantly higher potential for creating powerful magnetic fields. This difference is crucial when designing magnetic devices for applications that require high magnetic field strengths, such as in medical imaging (MRI machines) or particle accelerators. For applications needing moderate to low magnetic field strengths that must be constant without energy input, permanent magnets (like those made from steel) are suitable. However, for applications where variable or extremely high magnetic field strengths are necessary, electromagnets are preferred despite their energy requirements. This distinction impacts technological solutions by dictating the choice between permanent magnets and electromagnets based on the specific needs of the application, balancing factors like power consumption, field strength, and operational flexibility.

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