Magnetic field intensity

Introduction

A part of the magnetic field that arises from the external current rather than the intrinsic properties is known as magnetic field intensity or magnetic field strength or magnetic intensity. Also, the area around the magnet or the area in which the magnetism effect is felt is the magnetic field. In a wire that carries current, the formation of magnetic fields takes place. The direction of induced current and the direction of the magnetic field is directly related to each other. Want to learn more about the magnetic field intensity and its other factors? Keep reading!

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History of Magnetic Field

The history of magnetic fields is long. Here are a few popular and important discoveries of scientists in magnetism.

• 1269 was the first time when the research of magnetic fields began. Petrus Peregrinus de Maricourt, a French scholar, discovered the magnetic field lines on the spherical magnet. When he saw that the magnetic field lines didn’t interact, he termed both poles as North and South poles. In addition to that, he discovered that even if the magnet is sliced, it will always have two poles – North and South poles.
• In 1600, William Gilbert of Colchester stated that Earth is a magnet and then published De Magnete, indicating magnetism.
• John Michell in 1750 proved that magnetic poles attract and repel each other.
• Again in 1785, Charles-Augustin de Coulomb said that these poles never got separated from each other.
• Then in 1781–1840, Siméon Denis Poisson had the first successful model of the magnetic field.

Later on, many other theories were given by the scientists. The last theory given by James Clerk Maxwell in 1861 explained the concept of electricity and magnetism. He gave some equations and formulas known as Maxwell equations that gave the relationship between the two.

Magnetic Field Lines

Generally, magnetic field lines are the imaginary lines represented around the magnet. The density of the lines gives the magnitude of the magnetic field present around the magnet. As per the concept of the magnetic field, the field present at the poles (south and north poles) is stronger than the field that is present away from the poles or at the centre. Let’s take an example to explain this concept better. Example: Take a sheet of white paper and attach it to the table. Then place the magnet, sprinkle some iron filings on the sheet and gently tap it. You will observe that the iron filings will make the magnetic field lines around the magnet. The image formed will represent the larger concentration of iron filings at the poles than that present at the centre or away from the poles.

Properties Of Magnet Field Lines

Here are a few properties of magnetic lines of force. Let’s discuss them in detail.

• The magnetic lines of force present around the magnet never intersect.
• The path of magnetic field lines is always the least resistive path. In the case of a bar magnet, the path of magnetic lines of force form closed loops starting from one pole to another.
• The magnetic field lines are the same length.
• The density of magnetic field lines will decrease as the lines of the magnetic field from high permeability region to low permeability region.
• The magnetic field lines move from the south to the north pole in the case of magnetic material. But this is the reverse in the case of air. The magnetic field lines will move from the north to the south pole in the air.

With the increasing distance from the poles, the density of magnetic field lines decreases. The magnetic field is a vector quantity because it has both direction and magnitude.

Magnetic Field In A Solenoid

Before we derive the solenoid’s magnetic field formula, let’s know “What is Solenoid?”. The solenoid is a coil of wire designed to produce a strong and high magnetic field around the magnet. In other words, it can be a type of electromagnet that is known to produce a strong magnetic field. When the wire is wrapped around the cylinder, and an electric current is passed through it, a strong magnetic field is produced. Here is the formula that represents the magnetic field in the solenoid case. B = μ0IN / L Where B is the magnetic field of the Solenoid, N is the number of the turns in the case of the solenoid; I is the coil’s current and L represents the length of the coil. It is proved that the magnetic field decreases with the increasing length of the coil, indicating their inverse nature. Outside the solenoid, the magnetic field is relatively less than inside the solenoid. For this reason, the magnetic field present at the outside of the solenoid is considered to be zero.

Conclusion

Magnetic field intensity is generally the strength of the magnetic field induced around the magnet. The SI unit of magnetic field intensity is amperes per meter or Tesla. Magnetic field lines play a vital role in denoting the direction of the magnetic field. We hope this article will help you learn more about magnetic field lines and magnetic field strength.

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