Magnetic Elements

Introduction

Magnetic Elements demonstrate that the Earth operates as a massive magnetic dipole, with its magnetic poles located close to its geographical ones. Because the magnetic needle’s north pole approximates the geographic north (NG), the magnetic pole near NG is the magnetic south pole of Earth Sm. In addition, the pole near SG is the Earth’s magnetic north pole (Nm).

Magnetic Susceptibility Formula

Magnetic susceptibility is an electromagnetic characteristic of a material that indicates how strongly it is magnetised. When a magnetic field induces magnetisation in a material, the magnetic susceptibility, a dimensionless proportionality factor that indicates the degree of magnetization, is measured. The magnitude of M is comparable to the applied field in the following statement:

Magnetic susceptibility formula –

X_m = M/H X_m: magnetic susceptibility M: magnetization H: field intensity A magnetic susceptibility ratio does not have a unit because it is the ratio of two quantities expressed in the same units. Magnetic susceptibility is affected by material and temperature characteristics. The Mathematical Term In this case, X_m = I if H = 1. In other words, a material’s magnetic susceptibility is the amount of magnetization it generates when exposed to a unit-strength magnet.

Magnetic Elements Categories

We can primarily classify the magnet into three categories:

• Permanent Magnet:

A magnet made of a permanently magnetised substance generates its continuous magnetic field. Ferromagnetic materials can be magnetised easily. Materials like iron, nickel, and cobalt are examples.

• Temporary Magnet:

A magnet that is only magnetised for a limited time is known as a temporary magnet. These magnets often consist of soft materials with low magnetic characteristics. They become magnetised for a brief time when a strong or permanent magnet comes near them.

• Electromagnet:

It is a magnet that generates a magnetic field due to current passing through it. Wire twisted into a coil is the most common electromagnet. As current travels through the wire, a magnetic field forms inside the coil. When we turn off the current, it goes away. Electromagnets are common in motors, generators, and hard disc drives.

Three Elements of Earth’s Magnetic Field

The size, as well as the direction of the Earth’s magnetic field, are determined by three elements of Earth’s magnetic field:

• The magnetic declination
• The magnetic inclination or the angle of dip
• The horizontal component of the Earth’s magnetic field

Magnetic Declination

Magnetic declination is the angle formed between the true north and magnetic north. On the horizontal plane, true north is never in the same place and varies based on the location on the Earth’s surface and the passage of time.

Magnetic Inclination

The angle of dip is another name for the magnetic inclination. It’s the angle formed by the horizontal plane on the Earth’s surface. The magnetic equator has a 0° angle of dip, while the magnetic poles have a 90° angle of dip.

Horizontal Component of the Earth’s Magnetic Field

It is the element that enables the free rotation of the magnetic needle along the vertical axis. However, horizontal components can change due to numerous factors. Let’s discuss some of them.

Variations in Earth’s Magnetic Field

The variations in the Earth’s magnetic field are caused by:

• Lunar Variations

The moon influences the variations in the Earth’s Magnetism. During a lunar eclipse, the tidal waves of the Earth can cause variations in the Earth’s ionised layer. This in turn can influence the magnetic field of Earth.

• Secular Variations

Several variations can occur in the Earth’s magnetic field due to the periodic change in the Earth’s axis. It moves from east to west. However, this takes place once every 960 years.

• Daily and Annual Variations

The Earth’s atmosphere is ionised by the sun’s ultraviolet rays. Due to this, the current is produced. The current results in a magnetic field. This change occurs every day and every year.

• Eleven-Year Sunspot Cycle

The phenomenon of sunspots takes place every eleven years. The sunspot is a region of a strong magnetic field. Hence, it causes a lot of variations in the Earth’s magnetic field.

• Irregular Variations

The sun may become very active during a particular period and show variations in the magnetic field. This may occur due to its ultraviolet rays ionising the atmosphere. This in turn affects the magnetic field of Earth.

Types of Magnetism

There are five types of magnetism:

1. Diamagnetic Material.
2. Paramagnetic Materials.
3. Ferromagnetic Materials.
4. Antiferromagnetic Materials.
5. Ferrimagnetic Materials.

Diamagnetic Material: Magnetic field repels the diamagnetic materials. An induced magnetic field is created in the opposite direction by the applied magnetic field, and it causes a repulsive force. Water, wood, petroleum, some forms of plastics, copper and mercury are diamagnetic materials. The water-based diamagnetic materials have less than or equal to one relative magnetic permeability. Hence, the magnetic susceptibility is less than or equal to 0. The magnetic susceptibility is negative for diamagnetic materials only. Non-magnetic materials are diamagnetic materials. They lack properties of permanent magnetisation without the external magnetic field. Paramagnetic Materials Paramagnetic materials have permanent atomic dipoles. They act individually and range in the direction of the external magnetic field. Chemical elements and compounds are paramagnetic materials. The relative permeability of magnets in them is slightly greater than one, and they exhibit small positive magnetic susceptibility. Therefore, they are attracted to magnetic fields. Ferromagnetic Materials The external magnetic field magnetises these materials. Magnetisation exists in some substances even after the removal of the external magnetic fields. Ferromagnetic materials are also subject to permanent magnetic properties, as atomic magnetic moments spin due to electron structure. The magnetic moments of the electrons line up parallel to one another even in the absence of an applied field. Ferromagnetic materials examples include iron, nickel, and cobalt. Antiferromagnetic Materials A substance is antiferromagnetic when the arrangement of atomic magnetic moments in it is in antiparallel directions. Antiferromagnets do not produce a magnetic field and possess zero net magnetic moments. Manganese oxide exhibits this behaviour. Ferrimagnetic Materials Opposing magnetic moments are not equal in ferrimagnetic materials. They possess permanent magnetization even in the absence of an external magnetic field and do not develop well-defined zero-field susceptibility.

Conclusion

This article explains the meaning of Earth’s magnetic field, magnetic elements, and its magnetic susceptibility formula. One can define the magnetic field at any point on the Earth in terms of specific quantities called magnetic elements of the Earth. The Earth’s magnetic field has a vital role in making the planet habitable. A magnetic field determines the direction of our compass needles. It also acts as a shield that deflects the solar wind that could otherwise devour the atmosphere.