In ancient times, magnets were considered a magical substance because there was an invisible force inside it that pulled the iron towards itself. At a present we are very well acquainted with a lodestone metal.
What is Magnet
Ferro metal is found naturally which is a very hard substance. The special property of this substance which attracts a piece of iron towards itself was discovered by the Greeks in the sixth century. At a present lodestone metal is playing a very important role in the field of electrical engineering without it,
We cannot imagine the present world, because construction of all electrical equipment, gadgets, and machines are making using the properties of electromagnetism. All electrical machines like DC generator, alternator, electric motor, transformer, relays, a radio, stabilizer, a microphone, television, telephone, and telegraph etc. are made on this law.
There are two types (1) permanent magnet (2) Temporary magnet.
The stone found naturally by the name of Lodestone is called a permanent type ferro matel. It is made in the lab from a mixture of aluminium, cobalt, and nickel materials.
Ferro matel that retain their attractive properties are called permanent ferro matel. Ferro matel that retain only a small portion of their attractive properties are called temporary inducement iron ore. Electro-ferrofluid matel is created artificially.
When copper or an aluminum wire is wrapped in iron ore and made into a coil and electric current is passed through this wire, then the iron ore becomes like ferro matel. The property of induction in iron ore remains as long as current flows in the coil.
What are the Characteristics of Magnet
Attractive property:
Materials like iron and cobalt are strongly attracted to this subtance. Paramagnetic materials, such as aluminum, are weakly attracted to this matel, while diamagnetic materials, like copper, are repelled. Understanding these behaviors is essential in various scientific and industrial applications.
Directive property:
Such matel have a natural tendency to align themselves with the Earth’s magnetic field. Its north-seeking pole will point toward the Earth’s geographic North Pole, while its south-seeking pole will point toward the South Pole. This property is the reason why compass needles, which are often magnetized, point north.
Shielding:
They are used to shielding or redirect magnetic fields. This property finds applications in electronic devices where unwanted magnetic interference needs to be minimized. Materials like mu-metal are employed for shielding purposes.
The Nature of Attraction and Repulsion:
At its core, magnetism is an invisible force that affects the behavior of objects without leaving visible traces. Objects attract and repel each other in mysterious ways, demonstrating a complex dance of invisible forces. Its allure is not bound by the constraints of visibility, creating a captivating mystery that has baffled thinkers throughout history.
Where are poles of a Bar Magnet Located
When lodestone matel is brought in near of iron, the lodestone matel always attracts the iron towards its end such an attractive property of an inducement shows that the ferrofluid matel has two poles. Ferro metal has two poles, one is a north pole and the other is a south pole.
This metal is tied to a thread and hangs freely, then after some time it becomes stable towards north and south direction, through this experiment its pole is known. The end of the lodestone metal facing north is called the North Pole and the end is facing south is called the South Pole.
some special properties of magnetic pole.
- Both poles of a lodestone matel have equal strength.
- The pole of the lodestone matel cannot be separated. If a ferrofluid metal is broken between both the poles then each will contain an n-pole at one end and an s-pole at the other.
- Like poles repel each other and unlike poles attract each other.
Use of Magnet
- This substance is used in a variety of electronic devices, including speakers, headphones, and microphones. They help in converting electrical signals into sound waves and vice versa.
- In Hard disk drives use this substance to encode and store data. The binary data is represented by the orientation of magnetic particles on the storage medium.
- Such materials are used in medical imaging equipment, such as MRI machines. They help generate to create detailed images of the internal structures of the body.
- Such substances are essential components in electric motors and generators. They are used to generating motion by interacting with electric currents.
- It is used in refrigerator door seals to create an airtight closure. This helps maintain the desired temperature inside the refrigerator.
- its commonly used in locks, such as those in doors and cabinets. Such type locks are often more durable and secure than traditional mechanical locks.
- Such types of substance are sometimes used in jewelry. Some people believe that wearing such jewelry may provide health benefits, although scientific evidence supporting these claims is limited.
- It's used in various toys and games, providing entertainment and allowing for interactive learning experiences.
Magnetic Field
When lodestone compass is brought in front of a ferro matel, there is a deflection in the compass. From this we see that attraction has its influence on the surrounding medium. The area around the lodestone matel within which the effect of attraction is felt is called magnetic field.
The inducement field is the area around a lodestone material that has a inducement effect. Its effect is also like that of electric field. Basically, the part of the magnetic pole in which force is experienced is called induction field.
Every magnet generates an invisible force field that extends into its surroundings. These fields influence nearby objects, aligning them with the magnetic poles. Understanding magnetic fields is crucial in designing technologies like MRI machines and magnetic levitation systems.
What is the Magnetic Lines of Force
The magnetic force which is the cause of attraction of a magnetic metal is shown by imaginary lines. The direction of these lines is determined by the compass needle.
List the Properties of Magnetic Field Lines
- Its lines of force from a closed loop.
- Its direction is from the North Pole to the South Pole outside the lodestone and inside the lodestone its direction is from the South Pole to the North Pole.
- Attractive or repulsive lines of force never intersect.
- Its lines of force contract longitudinally and subsequently widen.
- Any ferrofluid material in which lines of force pass easily.
- The lines of force, are like stretched rubber bands,
Gauss Law of Magnetism
There is two law.
- In a ferrofluid metal, like poles repel each other while unlike poles attract each other.
- The force between two magnetic poles is directly proportional to the product of their pole strength and inversely proportional to the square of distance between their centres.
Let the mag. strength of two poles of a lodestone be m_{1} and m_{2}.if placed these pole between d distance.
Then according to law
F\propto \dfrac{m_{1}m_{2}}{d^{2}}
Where K is constant.Its value depends on the medium around it.K is also known as permeability.
Where K=\dfrac{1}{4\pi \mu _{0}\mu _{r}}
\mu _{0} is the absolute permeability of a vacuum or air
\mu _{r} is the relative permeability of the surrounding medium.
The value of \mu _{0}=4\pi \times 10^{-7}H/m and \mu _{r} value depends on media.
Then F=\dfrac{m_{1}m_{2}}{4\pi \mu _{0}\mu rd^{2}} Newtons for medium
=\dfrac{m_{1}m_{2}}{4\pi \mu _{0}d^{2}} Newtons for a vacuum.
The Unit of Magnetic Flux
The collective form of all its lines of force is called magnetic flux. The more the lines of force, the more will be the flux, as well as higher the strength of its field.its flux is denoted by \phi.the unit of flux is weber.
One Waber = 10^{8} lines of force.
Magnetic Flux Density(B)
The mag. flux per unit area = mag. flux density. it is represented by B
Mag. Flux density(B) = \dfrac{magnetic\left( \phi \right) }{area\left( a\right) }
The unit of its flux density is wb/m^{2} or tesla.
When any coil this flux passed there are three condition are generated.
(i) When the position of the coil is perpendicular to the direction of flux then in this condition maximum flux will pass through the coil.
Mag. Flux \left( \phi _{n}\right) = BA wb
(ii) when plane of the coil is inclined at an angle \theta to the flux direction.in this condition flux(\phi) through the coil is
\phi =BA\sin \theta wb
(iii) when plane of the coil is parallel to the flux direction \theta =0^{\circ } so in this condition flux will pass through the coil is
\phi =BA{\sin 0^{\circ }}
=0
Unit of Magnetic Pole Strength
By The law of magnetism, we see that the force between the lodestone pole’s depends on the poles strength. weber is also the unit of pole strength.
Alnico Alloy
Alnico is the alloy from which permanent lodestone are made. Alnico full form a mixture of aluminium, nickel, cobalt, iron, copper, and titanium.
Due to its small temperature coefficient and excellent inducement properties, it is used in making permanent ferro material appliances.
The biggest advantage of Alnico metals is that their coercivity and Curie temperature are very high. the high curie temperature means that the materials retain its lodestone properties even high temperature.
It can be easily demagnetized as well as magnetized because its coercive force and demagnetization curve are non-linear, this is its biggest drawback. Alnico are three types.
- cast alnico
- bar alnico
- sintered alnico
many properties are made from alnico such microphones,electric guitar pickups,electric motors,loudspeakers,sensors etc.
Permalloy
permalloy is a highly ferrofluid material made from a alloy of nickel,iron and molybdenum.It is used in making electro ferro matel core. Core loss and eddy current loss of such metal are very less. At present it is used in large quantities in making transformer core, relay, amplifier, loudspeaker, yoke etc.