Magnetism in Physics is defined as the property of the material that is responsible for the magnetic behaviour of the magnets. Magnetism is defined as the force that is produced by the moving charge and it attracts or repels other magnets and moving charge. Initially, magnetism is defined as the property of some material to attract or repel some other magnets. Later it was discovered that all the moving charges are considered to be magnets and their property of attraction or repulsion is called magnetism.
Here, in this article, we will learn about, Magnetism Definition, History of Magnets, Causes of Magnetism, Magnetic Materials, Properties of Magnets and others in detail.
What is Magnetism?
Magnetism is a phenomenon induced by the force exerted by magnets, which produces fields that attract or repel other metallic objects. It occurs as a result of electrically charged particles. A magnetic field exerts a force on other metallic objects called the Lorentz force this force depends on the strength of the magnetic field and the velocity of the charged particle. For any magnets.
- Like poles repel each other.
- Opposite poles attract each other.
Magnetism Definition
Magnetism in general is defined as the phenomenon associated with the magnetic fields. We know that magnetic fields are produced by moving electric charges and thus magnetism is the property of the moving charged particle that produces a force that is exerted on the other metallic material inside the magnetic field of the moving charge.
History Of Magnetism
Everything around us is made up of electrons and they are continuously moving. So one might ask why everything around us is not a magnet including ourselves. The answer to this is, that individual electrons moving around any object behave as a magnet but overall all these small magnets cancel out each other's magnetic property and thus not all material behaves as a magnet.
In some materials, all the electrons are arranged in such a way that they do not cancel each other and they are called ferromagnetic material. These ferromagnetic materials are called permanent magnets as they attract other metallic materials naturally. The property of magnetism is first observed in a material called Magnetite(Fe3O4) hence the name magnets. These magnetite is scattered all around the Earth's crust and was first noticed by a shepherd in Greece.
Magnetism Properties
The various properties of the magnets are,
Attractive Property: Magnets attracts other ferromagnetic and paramagnetic substances.
Repulsive Property: Like poles of a magnets always repel each other.
Magnetism of Earth
Earth have a magnetic field and this is observed whenever we pin a compass it always arranged in the north south direction this is because of the Earth magnetism. Geographical North Pole of the Earth is the magnetic South Pole of the Earth and geographical South pole of the Earth is the magnetic North pole of the Earth.
What is Magnetic Field?
Magnetic field or magnetism field is defined as the space or region around a magnet in which magnetic force is applied to another metallic material.
The magnetic field or magnetism can be represented in a variety of ways. It may be represented mathematically as a vector field that can be displayed as various sets on a grid. Another method is to utilize field lines. Magnetic field lines never cross one other. The denser the magnetism field lines the more strength of the magnetic field they represent. The magnetic field of the bar magnet is shown in the image added below,
Unit of Magnetic Field
Magnetic field is measured by determining the intensity and direction of the magnetic field. The measurement is required because each magnetic field differs from the others. In a magnetic field, we measure two things that are,
- Magnetic Field Strength(H) is measured in Ampere/meter.
- Magnetic Flux Density(B) measured in Tesla.
Magnetic Field Lines
Magnetic field lines are a type of visual representation of magnetic fields. They describe the magnetic force direction and magnetic force strength at any particular point near the magnet.
The magnitude of the field is indicated by the density of the lines. For example, at the poles of a magnet, the magnetic field is stronger and denser. It becomes weaker as we go away from the poles, and the lines become less dense.
Magnetic Field Line Properties
There are various properties of the magnetic field lines and some of them are,
- Magnetic field lines never cross one other.
- Magnetic field lines are always closed loops.
- The density of the field lines reflects the field's intensity.
- Magnetic field lines always arise from or begin at the north pole and end at the south pole.
Magnetic Materials
All the materials around us can be categorized into three types that are,
- Diamagnetic Materials
- Paramagnetic Material
- Ferromagnetic Materials
Diamagnetic Material: In general most of the materials around us have diamagnetism. In this material, they have paid electrons and thus they have no magnetic property. Examples of Diamagnetic Materials are Copper, Gold, Silver, etc.
Paramagnetic Materials: The materials that have unpaired electrons are called paramagnetic materials and they show paramagnetism, i.e. they experience some force inside the magnetic field of other magnets. The magnetic moment of the electrons does not align in the case of the paramagnetic materials. Examples of Paramagnetic materials are Magnesium, Lithium, etc.
Ferromagnetic Materials: There are very few materials that have ferromagnetism and they can be made permanent magnets. In ferromagnetic materials they have unpaired electrons and their magnetic moment is free to align itself freely. Examples of Ferromagnetic materials are, Iron, Cobalt, and Nickel.
Magnetism Types
There are five types of magnetism that are,
- Diamagnetism
- Paramagnetism
- Ferromagnetism
- Anti-Ferromagnetism
- Ferrimagnetism
Diamagnetism
Diamagnetism is the property of the Diamagnetic Materials. These materials have paired electrons and they do not experience force in magnetic field. In a diamagnetic substance there are no permanent magnetic dipole moment of the electron.
Paramagnetism
Paramagnetism is the property of the material that have unpaired of the electrons. These material are called the paramagnetic material. Here in these material there are magnetic moment of the electrons and they tends to be arranged randomly such that there overall magnetic moment cancel out each other.
Ferromagnetism
Magnetism of the ferromagnetic material is called the ferromagnetism. These materials have the tendency to to arrange themselves in the influence of an external magnetic field and thus increase magnetic moment of the material.
Anti-Ferromagnetism
Anti-ferromagnetism is the property of the material in which the individual magnetic moment of the material arranges itself such that its magnitude is the same with its adjacent one but the direction is opposite, which cancels the overall magnetism of the material.
Ferrimagnetism
Ferrimagnetism is the property of the material in which the adjacent magnetic moment of the electrons are opposite to each other and their magnitude is not the same. thus, the material shows the overall magnetism and experiences some force in the external magnetic field.
Magnetic Force
The magnetic force is the attraction or repulsion force that exists between electrically charged particles as a result of their motion.
The magnetic force between two moving charges is defined as the force imposed on one's charge by the magnetic field generated by the other. This force is responsible for magnets attracting or repelling one another.
A compass, a motor, the magnets that keep things on the refrigerator, railway lines, and new roller coasters are all examples of magnetic force. A magnetic field is created by all moving charges, and the charges that travel across its areas experience a force. Depending on whether the force is attractive or repulsive, it might be positive or negative. The magnetic force of an item is determined by its charge, velocity, and magnetic field.
Force on Moving Charge
A charge experiences a force if it travels across a magnetic field. The force on a moving charge in a magnetic field is given by the formula,
F = q.v.B.sin θ
where,
- q is the Charge
- B is the Magnetic Field
- v is the Velocity of the Charge
- θ is the Angle Between Magnetic Field and Velocity of Charge
Magnetic Effect Of Current
Moving charge produces electric field and this shown in the experiment added below:
In the above material if the current pass through the copper wire then it deflects the compass placed near it. This shows that moving charges produces electric filed.
Right-Hand Rule
The right-hand Rule is used to determine the direction of the force (F) in a magnetic field. Right-Hand Rule states that,
Point your pointer finger towards the direction of the charge's motion. Between v and B, rotate your middle finger away from your index finger. Hold your thumb parallel to the plane produced by your index and middle fingers. If the charge q is positive, your thumb will point in the direction of the force (F). The image added below shows the Right Hand Rule.
Uses of Magnets
Various uses of the magnets are,
- Magnets is used in magnetic compass to gets the direction.
- Magnets are used in Speakers and others.
- Magnets are used in Electric Motors and Electric Dynamos.
- Electromagnets are used in Maglev Trains and others.
- Magnets are used in construction industries.
One of the most important use of Magnetism is, Magnetism Separation of various objects.
Magnetism Separation Method
Magnetism Separation is the process of separating various metallic impurities and other thing form the ore, or separating metallic ore from the non-metallic impurities. Eg. Iron metal is separated from magnetite by magnetism separation method.
Read More,
Example 1: Find magnetic force on a charged particle travelling at 5 m/s in a magnetic field of 2 T? Its field's direction is the same as the route of the charged particle. (Given q = 40 C)
Solution:
Given:
- Charge, q = 40 C
- Velocity, v = 5 m ⁄ s
- Magnetic Field, B = 2 T
Because the second particle's route difference is the same as the direction of its field, θ = 30°
F= q v B sin θ
F = 40 × 5 × 2 × sin 0°
F = 0
Hence, the magnetic force of charged particles is 0 N.
Example 2: Find the particle force on a charged particles travelling at (v) 20 m/s in a magnetic field of (B) 10 T? If the angle between q and B is 30° (Given q = 4 C)
Solution:
Given:
- Charge, q = 4 C
- Velocity, v = 20 m ⁄ s
- Magnetic Field, B = 10T
- θ = 30°
F= q v B sin θ
F = 4 × 20 × 10 × sin 30°
F = 400 N
Hence, the magnetic force of charged particles is 400 N.
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