Permanent Magnet
Last Updated :
15 Jan, 2024
Permanent Magnets are materials that can create a magnetic field even if the magnetization force is removed. Unlike other magnets, it keeps its magnetic power all the time. They are made of hard ferromagnetic materials, for example, Ferrite and Alnico.
Distinguished by their natural capacity to generate a magnetic field, permanent magnets effortlessly attract materials such as iron and steel. In this article, we will learn what is Permanent Magnets, their properties, applications, advantages, and disadvantages. We will also learn what how a Permanent Magnet differ from Non Permanent Magnet and Electromagnet.
What are Permanent Magnets?
Permanent Magnets are objects that naturally produce a magnetic field. They can attract certain materials like iron and steel without needing an external influence. Unlike temporary magnets, which require exposure to a magnetic field to become magnetic, permanent magnets maintain their magnetic properties consistently over time. This permanent magnetic property in them is due to the aligned spin of the ferromagnetic material of which they are made up of.
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Permanent Magnets Definition
A permanent magnet is a material or object that possesses inherent magnetic properties, allowing it to generate a magnetic field continuously without the need for an external power source.
This magnetic field enables the magnet to attract certain materials, such as iron or steel, and exert a force on them.
Permanent Magnet Examples
The examples of Permanent Magnets are mentioned below:
- Refrigerator Magnets: The magnets used to attach notes and pictures to refrigerators are often permanent magnets.
- Bar Magnets: Straight or bar-shaped magnets are simple examples of permanent magnets.
- Horseshoe Magnets: These magnets are shaped like a horseshoe and are commonly used in various applications.
- Alnico Magnets: Made from a combination of aluminum, nickel, and cobalt, these magnets are known for their strong magnetic properties.
- Ferrite Magnets: These are often found in speakers, refrigerator door seals, and other household items.
- Neodymium Magnets: Known for their strong magnetic field, neodymium magnets are used in various electronic devices and industrial applications.
- Ceramic Magnets: Also called ferrite magnets, these are commonly used in motors, speakers, and other everyday devices.
Properties of Permanent Magnet
Permanent magnets possess several key properties that define their behavior and usefulness in various applications. Here are some of the fundamental properties of permanent magnets:
- Magnetic Field: Permanent magnets generate a magnetic field around them, creating a region where magnetic forces can influence nearby objects.
- Magnetic Poles: Every permanent magnet has a north pole and a south pole. The magnetic field lines flow from the north pole to the south pole outside the magnet.
- Attraction and Repulsion: Like poles repel each other, and opposite poles attract. This behavior is a fundamental characteristic of magnetic interactions.
- Retentivity: Permanent magnets have a property called retentivity, meaning they can retain a certain level of magnetization even after being exposed to an external magnetic field.
- Coercivity: This property refers to the ability of a material to resist demagnetization. Permanent magnets typically have high coercivity, ensuring their stability over time.
Magnetic Behaviour of Permanent Magnet
The behavior of a permanent magnet is defined by its ability to create a magnetic field. Every magnet has a north and south pole, and these poles attract or repel each other. The magnet keeps its magnetic properties over time, and it can resist losing its magnetism. This stability makes permanent magnets useful in everyday items like fridge magnets and more advanced technologies like electric motors.
- The magnetic field lines, which flow from the north pole to the south pole outside the magnet, help visualize the path of the magnetic force, forming a continuous loop around the magnet.
- The magnetic field line inside the magnet is from south pole to north pole thus making a close loop of magnetic field lines.
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NdFeB Permanent Magnet
An NdFeB permanent magnet, also known as a neodymium magnet ,NIB or Neo magnet , is a really strong type of magnet.
- It’s made from a mix of neodymium, iron, and boron.
- These magnets are super powerful and are used in lots of things like electronics, motors, medical tools, and other industrial stuff.
- Because they have such a strong magnetic field, NdFeB magnets play a big role in many of the gadgets and devices we use today.
Rare Earth Permanent Magnet
Rare Earth Permanent Magnets are strong and durable magnets made from special materials that include elements like neodymium and samarium.
- These magnets are powerful and used in various things like electronics and motors because of their strong magnetic properties.
- They are not actually rare; it’s just a name from the elements they contain.
- The term “rare earth” refers to the fact that these magnets contain elements from the lanthanide series of the periodic table, which were initially considered rare but are found in abundance in the Earth’s crust.
Advantages and Diadvantages of Permanent Magnet
The advantages and disadvantages of Permanent Magnet are tabulated below:
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Constant Magnetism: Maintain their magnetic properties without an external power source.
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Temperature Sensitivity: Performance can be affected at extreme temperatures.
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High Magnetic Strength: Certain types, like neodymium magnets, exhibit strong magnetic fields.
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Cost: Some high-performance materials can be expensive.
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Compact Size: High magnetic flux in a small and lightweight package.
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Demagnetization Risk: Susceptible to demagnetization under certain conditions.
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Long Lifespan: Retain magnetism over a long period.
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Limited Shape Flexibility: May have limitations in shape compared to flexible materials.
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Energy Efficiency: Efficient in various applications, contributing to energy savings.
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Environmental Impact: Extraction and production of rare-earth magnets can have environmental consequences.
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Diverse Applications: Used in a wide range of technologies, from electronics to renewable energy.
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Limited Adjustability: Magnetism cannot be easily adjusted or turned off.
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Reliability: Stable and reliable magnetic properties under normal operating conditions.
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Weight: Some high-strength magnets can be heavy.
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Low Maintenance: Generally low maintenance compared to electromagnets.
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Limited Recycling: Recycling of certain materials may be challenging.
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Difference between Permanent Magnet and Electromagnet
Permanent Magnet is the one which naturally produce magnetic field around it while electromagnet is the one which produces magnetic field due to the effect of electric current. The key differences between Permanent Magnet and Electromagnet are listed in the following table:
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Inherent magnetic properties of material.
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Magnetic field created when an electric current flows through a coil of wire.
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Fixed magnetism; cannot be easily altered.
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Magnetism can be controlled by adjusting the electric current in the coil.
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Does not require an external power source.
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Requires an external power source (electric current) to maintain its magnetic field.
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May have varying magnetic strengths.
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Can be designed for variable and strong magnetic fields, depending on the current flowing through the coil.
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Commonly used in everyday items (e.g., refrigerator magnets).
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Widely used in devices where a controllable magnetic field is needed (e.g., electric motors, MRI machines).
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Bar magnets, horseshoe magnets, neodymium magnets.
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Solenoids, electric cranes, magnetic locks.
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Learn, Permanent Magnets and Electromagnets.
What is Non-Permanent Magnet?
A non-permanent magnet, often referred to as a temporary or soft magnet, is a material that can be easily magnetized but loses its magnetism quickly when the external magnetic field is removed. These materials do not retain a significant amount of magnetism on their own and are used for temporary purposes.
Common examples of non-permanent magnets include:
- Soft Iron: Soft iron can be easily magnetized but loses its magnetism rapidly when the external magnetic field is removed.
- Magnetic Rubber: Rubber compounds containing tiny particles of a ferromagnetic material can exhibit temporary magnetism.
- Magnetic Paper: Paper impregnated with ferromagnetic particles can become temporarily magnetized when exposed to a magnetic field.
Difference between Permanent and Non-Permanent Magnet
The difference between Permanent and Non-Permanent Magnet is tabulated below:
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Inherent and enduring magnetic properties.
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Easily magnetized but loses magnetism quickly when the external magnetic field is removed.
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Made of materials like neodymium, ferrite, or alnico.
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Soft iron, magnetic rubber, or materials that can be temporarily magnetized.
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Retains significant magnetism over time.
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Exhibits magnetism temporarily and loses it quickly.
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Commonly used in everyday items (e.g., refrigerator magnets, motors).
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Used in applications where temporary magnetism is sufficient (e.g., magnetic door latches, some scientific experiments).
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Neodymium magnets, ferrite magnets, alnico magnets.
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Soft iron, magnetic rubber, magnetic paper.
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Permanent Magnets Applications
The various applications of Permanent Magnets are mentioned below:
- Electronics: Used in the manufacturing of speakers, headphones, and various electronic devices to convert electrical energy into sound.
- Electric Motors: Essential components in electric motors found in appliances, power tools, and electric vehicles.
- MRI Machines: Critical for generating a strong and stable magnetic field in medical imaging devices like Magnetic Resonance Imaging (MRI) machines.
- Magnetic Separators: Employed in industries such as mining and recycling to separate ferrous materials from non-ferrous materials.
- Generators: Used in the production of electrical generators to convert mechanical energy into electrical energy.
- Sensors: Incorporated into various sensors for position sensing, speed sensing, and other applications.
Permanent Magnet for Motors
A permanent magnet motor is an electric motor that uses permanent magnets to generate a magnetic field.
- Unlike traditional motors that rely on electromagnets, these motors have magnets with a constant magnetic strength.
- The interaction between the magnetic fields produced by the permanent magnets and the electrical current flowing through the motor creates mechanical rotation, making these motors efficient and widely used in various applications, such as electric vehicles and appliances.
- Permanent Magnets play a crucial role in electric motor, contributing to their efficiency and performance. There are two main types of permanent magnets used in motors:
Neodymium Iron Boron (NdFeB) Magnets
The advantages of NdFeB Magnets are mentioned below:
- High magnetic strength: NdFeB magnets are known for their exceptional magnetic properties, making them suitable for high-performance motors.
- Compact size: They offer a high magnetic flux in a small and lightweight package, contributing to the overall efficiency of the motor.
Applications of Neodymium Iron Boron (NdFeB) Magnets Motor
- Used in small motors, such as those in electric vehicles, power tools, and various consumer electronics.
Samarium Cobalt (SmCo) Magnets
Advantges of Samaramium Cobalt Magnets in motors are mentioned below:
- High-temperature stability: SmCo magnets can withstand higher temperatures compared to NdFeB magnets, making them suitable for applications where motors may operate at elevated temperatures.
- Corrosion resistance: SmCo magnets are less susceptible to corrosion, making them suitable for certain environments.
Applications of Samarium Cobalt Magnet Motors are mentioned below:
- Aerospace applications, high-performance motors, and areas where high-temperature stability is crucial.
Permanent Magnet Generator
In generators, permanent magnets are commonly used to create a magnetic field, which is a crucial component for generating electrical power. Two main types of permanent magnets are often employed in generators:
Neodymium Iron Boron (NdFeB) Magnets Generator
Advantages of (NdFeB) Magnets Generator is mentioned below:
- High magnetic strength: NdFeB magnets provide strong magnetic fields, contributing to efficient power generation.
- Compact size: They offer a high magnetic flux in a small and lightweight package, allowing for compact generator designs.
Applications of (NdFeB) Magnets Generator is mentioned below:
- Small-scale generators, wind turbine generators, and various portable or residential power generation systems.
Ferrite (Ceramic) Magnets Generator
Advantages of Ferrite Magnet Generator are mentioned below:
- Cost-effective: Ferrite magnets are generally more cost-effective than NdFeB magnets.
- Good resistance to corrosion: Ferrite magnets are less prone to corrosion, making them suitable for certain environments.
Applications of Ferrite Magnet Generators are mentioned below:
- Often used in smaller or less demanding generator applications, such as in some wind turbine generators or small-scale residential generators
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Permanent Magnets – FAQs
1. How to De-magnetize a permanent magnet?
To de-magnetize a permanent magnet, you can expose it to high temperatures or strong magnetic fields. Heating it or hitting it can help break the alignment of its magnetic atoms, making it lose its magnetism.
2. Do Permanent Magnets lose its Magnetism?
Yes, over a very long time, a permanent magnet can gradually lose some of its magnetism. Factors like heat, strong impacts, or exposure to certain conditions can make it weaker.
3. What are 5 Permanent Magnets?
Here are five types of permanent magnets commonly used in various applications:
- Neodymium Magnets (NdFeB)
- Samarium Cobalt Magnets (SmCo)
- Alnico Magnets
- Ferrite Magnets (Ceramic Magnets)
- Flexible Magnets
4. What is Difference between a Permanent Magnet and Electromagnet?
The major difference between a Permanent Magnet and Electromagnet is that Permanent Magnet has magnetic field even if there is no magnetization while Electromagnet shows magnetic property in the presence of electric current only
5. How Permanent Magnets are made?
Permanent magnets are typically made using materials with special magnetic properties. The most common types of permanent magnets are ferrite, alnico, samarium-cobalt, and neodymium-iron-boron.
6. What is a Permanent Magnet and a Temporary Magnet?
A Permanent Magnet is the one which has magnetic properties even in the absence of magnetic force while Temporary Magnets are those which show magnetic properties only in the presence of Magnetizing Force
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