What is a Permanent Magnet

 

Title: What is a Permanent Magnet

Introduction:

Magnetism has become popular to humans for centuries, from the early discovery of lodestone in ancient times to the sophisticated magnets used in modern technology. One key player in the field of magnetism is the permanent magnet. Permanent magnets are  very essential components in various applications, ranging from household items like refrigerator magnets to advanced technologies like MRI machines and electric motors. In this article, I will explain What is a Permanent Magnet, it’s properties, manufacturing processes, and its diverse applications.

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Explanation: 

To start today’s article What is a Permanent Magnet Let,us first know,some basic concepts ,

What is a magnet?

A substance or an object which always attracts iron,nickal and iron’s compound, when suspended freely it always remains in the direction of north and south.

Properties of magnet:

(i) Magnet always remains in north and south direction when it is suspended freely.
(ii) Magnets always attracts iron and iron’s compound.
(iii) All magnets has two poles and they are south pole and north pole.
(iv)Two different pole  magnets (one is south pole and other is north pole and vise versa)always attracts themselves and two same pole  magnets(both are either north or south) repel each other.

What is pole of  a magnet?

The pole is a region where the force of attraction or repulsion of a magnet is maximum.

What is magnetic lines of force?

Magnetic lines of force are some imaginary lines which indicates the magnetic field of a magnet, which come out from north pole and enters to south pole.

Properties of Magnetic lines of force:

(i)Magnetic lines of force are imaginary lines.
(ii) Two magnetic lines of force never intersect eachother.
(iii) They come out from north pole of a magnet and enters to south pole of the magnet.

Basics of magnetism:

To illustrate permanent magnets, it's crucial to us that we must have a solid understanding of magnetism itself. In the atomic level, magnetic moments arise from the intrinsic spin of electrons and the movement of these charged particles around atomic nuclei. When these magnetic moments align in a material, it results in macroscopic magnetization. There are three main types of magnets: temporary, electromagnets, and permanent magnets.

Temporary magnets:

The materials which can be easily magnetized by applying external magnetic field but lose their magnetism when the external magnetic field is removed. Common examples include iron and steel. 

Electromagnets:

These magnets are created by an electric current flowing through a coil of wire. The magnetic field of these magnets are present only when the current is flowing, unlike temporary magnets.

 Permanent magnets:

The substance or material which attracts iron and iron’s compound,when suspended freely always remain in north -south direction and produce magnetic field is known as magnets.The magnets which never loss their magnetic properties and always  retain their magnetization in the absence of an external magnetic field are known as permanent magnet.

What makes a magnet permanent?

Permanent magnets possess their unique properties to the alignment of magnetic domains within the material. A magnetic domain is a space within a material where the magnetic moments of atoms are aligned in the same direction, producing a net magnetic field. In the absence of an external magnetic field, these domains tend to align randomly, resulting in no macroscopic magnetization.
However, in the manufacturing process of permanent magnets, the magnetic domains are generally aligned to create a strong and stable magnetic field. This alignment is achieved through various methods, such as heat treatment, applying an external magnetic field, or a combination of both.

Types of permanent magnet:

There are several types of permanent magnets exist, each with its unique characteristics and applications. The most common types of permanent magnet  are:

Ferrite Magnets:

Ferrite magnets, which are also known as ceramic magnets, are made from a compound of iron oxide and other elements like strontium or barium. They are relatively inexpensive and broadly  used in applications like refrigerator magnets and small electric motors.

Alnico Magnets:

Alnico magnets are made up of aluminum, nickel, and cobalt, along with iron and other elements. They are widely known for their strong magnetic field and high-temperature stability. Alnico magnets are used in various industrial applications, including sensors and guitar pickups.

Neodymium Magnets:

Neodymium magnets, are commonly referred to as NdFeB magnets, are the most powerful type of permanent magnets commercially available every where. They are made from an alloy of neodymium, iron, and boron. Neodymium magnets are found in the applications of computer hard drives, headphones, and even magnetic therapy products.

Samarium-cobalt magnets are another type of rare-earth magnet, consisting of samarium, cobalt, and traces of other elements. They can produce high magnetic strength and excellent resistance to demagnetization at elevated temperatures. These magnets are utilized in aerospace and military applications.

Samarium-Cobalt Magnets:

Samarium-cobalt magnets are another type of rare-

earth magnet, consisting of samarium, cobalt,and 

traces of other elements. They can produce high 

magnetic strength and excellent resistance to 

demagnetization at elevated temperatures. These

magnets are utilized in aerospace and military

applications.

Manufacturing Process:

The process of manufacturing permanent magnets is intricate and involves several steps to ensure the desired magnetic properties, Where the specific procedures may vary based on the type of magnet being produced.

A general outline includes the following important steps:

Raw Material Preparation:

The first step includes gathering the raw materials needed for the specific type of permanent magnet. For instance, neodymium magnets require a mixture of neodymium, iron, and boron in carefully controlled proportions.

Melting and Alloying:

After completing preparation the raw materials are then melted together in a furnace to form a molten alloy. This alloy is carefully controlled to achieve the desired composition for the magnet.

Milling:

The alloy is crushed into a powder, which is then milled to get a fine particle size. This step is crucial for ensuring the homogeneity of the material.

Pressing:

In this step the milled powder is pressed into the desired shape using a die. This results in a green compact, which is a preliminary form of the magnet.

Sintering:

The green compact is dryed to high temperatures in a process called sintering. During sintering, the particles fuse together, and the magnet begins to take on its final properties.
The final step is set up for magnetizing the material. This is typically done by exposing the material to a strong external magnetic field, aligning the magnetic domains and creating a permanent magnet.

After sintering, the magnet may undergo additional machining to receive precise dimensions and surface finishes.

Machining:

After sintering, the magnet may undergo additional machining to receive precise dimensions and surface finishes.

Magnetization:

The final step is set up for magnetizing the material. This is typically done by exposing the material to a strong external magnetic field, aligning the magnetic domains and creating a permanent magnet.

Properties of Permanent Magnets:

Permanent magnets show several key properties that make them essential in various applications:
The magnetic strength of a permanent magnet is a measure of its ability to attract or repel other magnetic materials. This property is vital for every magnet which is influenced by some factors such as the material composition and manufacturing process.
Coercivity is another important property of permanent  magnet by the virtue of which help to measure of a magnet's resistance to demagnetization. High coercivity ensures that the magnet retains its magnetic properties over time, even in the presence of external factors.
The Curie temperature is the temperature at which a material loses its magnetic properties. So it is very important to us to understand the Curie temperature,which is crucial for applications that involve exposure to high temperatures.

Magnetic Strength:

The magnetic strength of a permanent magnet is a 
measure of its ability to attract or repel other magnetic materials. This property is vital for every magnet which is influenced by some factors such as the material composition and  manufacturing process.

Coercivity:

Coercivity is another important property of permanent  magnet by the virtue of which it helps us to measure of a magnet's resistance to demagnetization. High coercivity ensures that the magnet retains its magnetic properties over time, even in the presence of external factors.

Curie Temperature:

The Curie temperature is the temperature at which
a material loses its magnetic properties. So it is very important to us to understand the Curie temperature,which is crucial for applications that
involve exposure to high temperatures.

Remanence:

Remanence, also known as magnetic polarization or magnetic induction, is the residual magnetization that remains in a magnet after the external magnetic field is removed. It is a vital  parameter for assessing the magnet's performance.

Magnetic Stability:

Magnetic stability suggests to the ability of a permanent magnet to maintain its magnetic properties over time. Stability is vital for ensuring the long-term functionality of magnetic components.

Applications of Permanent Magnets:

The large number of needness of permanent magnets makes them essential in a wide range of applications across various industries. Some notable applications include:

Electric Motors and Generators:

Permanent magnets play a vital role in electric motors and generators used in appliances, automobiles, and industrial machinery. Due to very strong magnetic fields generated by these magnets contribute to the efficiency and performance of these devices.

Magnetic Resonance Imaging(MRI):

In the field of medicine, permanent magnets are integral components of MRI machines. The powerful magnetic fields which are produced by these magnets enable detailed imaging of internal body structures, aiding in diagnosis and medical research.

Electronics and Telecommunications:

Permanent magnets are found in a large numer of electronic devices, including speakers, headphones, and computer hard drives. Their use in these applications contributes to the functionality and miniaturization of electronic components.

Magnetic Separators:

In industries namely, mining and recycling, permanent magnets are used in magnetic separators to separate and recover ferrous materials from non-ferrous materials. This enhances the efficiency of material processing and recycling operations.

Sensors and Actuators:

Permanent magnets are broadly used in sensors and actuators, contributing to the precision and reliability of devices such as accelerometers, speed sensors, and position sensors.

Renewable Energy:

Permanent magnets are used in the generators of wind turbines, contributing to the generation of renewable energy. The high magnetic strength of neodymium magnets, in particular, makes them well-suited for this application.

Challenges and Future Developments:

While permanent magnets offer numerous advantages, there are also challenges associated with their production and use. One significant challenge is the reliance on rare-earth elements, particularly for high-performance magnets like neodymium magnets. The extraction and using  of rare-earth elements raise environmental and geopolitical concerns.
Researchers and engineers are actively exploring alternative materials and manufacturing techniques to address these challenges. This includes the development of magnet recycling methods and the investigation of non-rare-earth-based magnet materials.

Conclusion:

In conclusion,I will tell that I have given a brief knowledge on What is a Permanent Magnet to all of you.Undoubtedly we can say that,

permanent magnets are fascinating components with a rich history and a myriad of applications. From the simple refrigerator magnet to the advanced technologies in medical imaging and renewable energy, permanent magnets play a vital  role in shaping our modern civilization. Understanding the principles behind their magnetism, the diverse types available, and the intricacies of their manufacturing process provides a deeper appreciation for these essential components .................

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FREQUENTLY ASKED QUESTIONs on Permanent Magnet:

(i).What is a permanent magnet in physics

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Answer:The substance or material which attracts iron and iron’s compound,when suspended freely always remain in north -south direction and produce magnetic field is known as magnets.The magnets which never loss their magnetic properties and always retain their magnetization in the absence of an external magnetic field are known as permanent magnet.

(ii).What is temporary magnet for Class 7?

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Answer:A magnet which loses its all magnetic properties when magnetic field is taken out from it is called a temporary magnet.e.g; An electro magnet, when power supply is cut off from it instantaneously it loses its magnetic properties and become temporary magnet.

(iii).What are 3 types of magnets?

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Answer:The 3 types of magnets are: (1) Temporary magnet.(2) Electro magnet (3) Permanent magnet.

(iv).Is nickel non magnetic?

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Answer:No,nickel is not non magnetic, it is a ferro magnetic metal which can be magnetized by the application of magnetic field.

(v).Why do magnets attract iron?

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Answer:Due to the influence of magnetic field of a magnet on Iron,Iron also get magnetized. So all magnets attract Iron and Iron compounds.

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