Science Behind It: How Do Magnets Work?

Magnets are everywhere in our daily lives, even if we don’t always notice them. From notes on refrigerators to powering complex machines, magnetism plays a vital role in technology, science and nature. But did you know that magnets were discovered 2,000 years ago?

The first known reference to magnetism can be traced back to ancient Greece. The Greeks discovered naturally-occurring magnets, called Lodestones, that attract iron. These mysterious stones are fascinated by early civilizations. In China, by the 4th century BC, people had begun to use Lodestones to make original compass, which helped them browse the vast ocean. This discovery revolutionized travel and trade, and even when the sky was cloudy and there were no visible stars, sailors could find their way.

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Over time, humans have learned to create artificial magnets, thus making significant advances in science and technology. Magnetism is crucial to countless applications these days – it is in your headphones, your phone, your car’s engine, and even in medical devices like MRI scanners. The Earth itself acts as a giant magnet that guides migratory birds and protects us from harmful solar radiation.

But what makes the magnet work? First let us understand what a magnet is.

What is a magnet?

Magnets are any material that creates a magnetic field, and it is an invisible force that can pull out or repel certain metals. Magnets can be found naturally or made artificially and have different types of magnets depending on how they behave.

Magnet type

Not all magnets are the same. Depending on how they behave, magnets can be divided into three main types:

1. Permanent magnet

They retain their magnetic properties for a long time because their domains remain consistent without any external influence.

Example:

• Rod magnet
• Refrigerator magnet
• Neon magnet (for hard drives and speakers)

2. Temporary magnet

When exposed to a strong magnetic field, these materials become magnetic, but lose their magnetic properties when the field is removed.

example:

• The iron nails that are rubbed with strong magnets will be magnetized.

3. Electromagnet

The electromagnet works by transferring the wire to the wire around the core. The current creates a magnetic field, and when the current is turned off, the magnetism disappears.

use:

• Electric motor
• MRI Machine
• Maglev train

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What is magnetism?

Magnetism is an invisible force that can attract or repel certain materials, especially metals such as iron, nickel and cobalt. Each magnet has two poles: one North Pole and one South Pole.

• The opposite pole attracts (north and south).
• Repulsive like a pole (north or south-south).

But why do magnets attract and repel each other? This force is caused by tiny moving charges inside the atom, but before we explore, let us understand how materials become magnets.

The Atomic Science Behind Magnetism

Source: U.S. Energy Information Management

Every object in the universe is made up of atoms, and inside them are tiny particles called electrons. Electrons move around the center of an atom, and their movements produce a small current. This motion creates a tiny magnetic field around each electron.

However, in most materials, electrons are rotated in pairs with opposite rotations. Since their magnetic fields cancel each other out, the material does not behave like a magnet.

But in some special materials, such as iron, nickel and cobalt, there are unpaired electrons. These unpaired electrons create tiny magnetic fields, and when they are aligned in the same direction, the material becomes magnetic.

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Ferromagnetic metal: the strongest magnet

The strongest magnets are made of ferromagnetic metals, which include iron, nickel, cobalt and some rare earth elements such as neon lights. What makes these metals unique is their ability to form and maintain a strong magnetic domain—small groups of atoms aligned in the same directions their magnetic fields.

In non-magnetic materials, these domains are arranged randomly, so their single magnetic force is cancelled. However, in ferromagnetic materials, these domains can be aligned with an external magnetic field to turn the material into a magnet.

Once magnetized, the ferromagnetic material retains its magnetic properties even after the external magnetic field is removed, making it ideal for producing permanent magnets. This is why iron and new magnets are used in powerful industrial applications.

But wait. Even if a single electron and magnetic domain contribute to magnetism, this alone is not enough to make the entire object work like a magnet. This is where domain alignment works.

What is the magnetic domain?

A magnetic domain is a small area inside a material, where the magnetic fields of many atoms are aligned in the same direction.

Think of it as a small number of people pointing in the same direction. If most people face different ways, there is no clear direction, but if they all face the same way, there is strong movement.

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In non-magnetic materials, these domains are arranged randomly, so their magnetic force is cancelled.

In magnetic materials like iron, these domains can be aligned to create a total magnetic field.

When you bring a strong magnet near the iron nail, it can temporarily force the fields inside the nail to line it up, thus turning it into a magnet. However, when the magnet is removed, the domain returns to the random arrangement and the nails lose their magnetism.

How we use magnetism today

Magnetism is not only a fascinating force of nature, but it revolutionizes modern technology. Here are some key applications:

Hard drives and data storage: Use tiny magnetic fields to store information.

Speaker and microphone: Use magnets to convert electrical signals into sound.

MRI machine: Use powerful magnetic fields to scan the inside of the human body.

Credit and subway cards: Contains magnetic stripes that store digital data.

Generators and motors: convert electricity into motion and vice versa.

Without magnetism, our world will look very different. There will be no generator, no radio waves, and no magnetic navigation system.

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Did you know that the earth itself is a huge magnet?

Image: NASA

In the depths of our planet, molten iron flows in the outer core. This motion generates current, thus creating the Earth’s magnetic field.

This geomagnetic field is responsible for:

• Make the compass work by aligning the needle with the magnetic poles of the earth.
• Protect us from harmful solar radiation and cosmic particles.
• Help migratory animals such as birds, sea turtles and bees sail over long distances.

The final thought

Magnetism is the fundamental force that shapes our world. From the ancient Rockwell discoveries to the advanced applications of today’s medicine, transportation and communication, magnets play a crucial role in human progress.

Whether it’s guiding early explorers across the sea, electric motor power or enabling data storage in computers, magnetism remains an important part of modern life. Next time you use a magnet, whether in a refrigerator or on a high-tech device, remember that a force of nature you witnessed has shaped our planet and technology for hundreds of years.

Source: https://dinhtienhoang.edu.vn
Category: Optical Illusion