What causes static electricity and Magnet
Properties of magnet
Magnet and magnetism
Natural and artificial magnets: Natural magnet is a black stone found in nature, which attracts small pieces of iron. This stone is iron oxide. It has no fixed shape, some substances are magnetized by artificial methods. These are called artificial magnets. These are of various shapes, such as rod magnet, horse shoe, magnetic needle etc. Their power to attract iron pieces is much higher than that of natural magnets.
Properties of magnet
The magnet attracts iron to itself: this property is called magnetism. The magnetism is highest near the ends of the magnet and less in the middle. There is no magnetism in the middle. The regions where the magnetization is highest at the ends of the magnet are called the poles of the magnet.
When hanging freely in the horizontal plane of the magnet, its north pole always stays to the north and south pole always stays to the south: the north pole is called the north pole and south pole is called south pole. The line joining the poles is called the magnetic axis.
The exogamous poles (north-south) of the two magnets attract each other and the homogeneous poles (north-north or south-south) repel each other.
Magnet causes magnetization by induction of magnetic materials.
A single magnetic pole has no existence – if we break a rod magnet into two parts, its north-south pole will not be separate, but each part will be a full magnet, which will have both poles, if we Even if each of these parts is broken again, each small part will be a full magnet. It is clear from this that we can never separate the poles of the magnet.
When a soft iron rod is placed in the same magnetic field, the density of magnetic force lines within the rod increases compared to outside. Conversely, when aluminum rods are placed in the same magnetic field, the density of magnetic force lines within the rod is reduced compared to outside.
The softness of soft iron is high.
Aluminum has a lower lubricity.
This property of a substance, due to which the density of magnetic force lines within it increases or decreases, is called magnetization. The magnetic force lines also pass through the vacuum. Therefore, vacuum also has the properties of magnetism.
A magnetic tendency is the physical amount that indicates how easily a substance absorbs magnetism. Materials like iron, aluminum, etc. can be magnetized by applying magnetic force. If the magnetizing force H and the intensity of the magnetic field produced is 1, then –
Magnetic trend x = 1 / H = constant
There are three types of matter based on magnetic tendency – antimagnetic, magnetic and iron-magnetized.
When these materials are magnetized by applying an external magnetic field, the magnetic field produced inside them is opposite to the externally charged magnetic field.
The direction of the induced magnetic field inside these substances is in the direction of the externally charged magnetic field.
These are materials in which the generated magnetic field is in the direction of the charged magnetic field. Therefore, the magnetic tendency of these substances is also positive and its value is much higher than 1. If these substances are placed in the external magnetic field, then they themselves become magnetized. Examples of these are iron, steel, nickel, cobalt etc.
When an iron-magnetized material is heated, such a heat occurs when its iron is converted into magnetized magnetism. This temperature is called Curie temperature. Curie heat values for iron and nickel are 770 ° C and 358 ° C, respectively.
Soft iron and steel
Soft iron soon becomes a magnet and soon its magnetism also ceases.
That is why soft iron is used to make temporary magnets. Electromagnets are made of soft iron only. Soft iron is used in electric bell, crossformer core, dynamo etc.
In contrast, steel hardens to form magnets and leaves its magnetism hard. Hence steel is used to make permanent magnets. For example, permanent magnets of loudspeakers, compasses, galvanometers etc. are made of steel only.
Each magnet has a decimal property, according to which, if a magnet is tied to its center of gravity and hung in such a way that it can rotate freely in the horizontal plane, we see that it always stops in the north-south direction. is. The reason for this is that our earth behaves like a large magnet.
It is as if a very large bar magnet is placed at the center of the earth, whose south pole is located towards the geographical north pole and north pole towards the geographical south pole. The force lines of the Earth’s magnetic field are equally spaced and parallel and face north.
At some place on Earth, the magnetic north is generally not exactly geographically north. The angle between these two directions is called the percussion. That is why in sea travel, sailors and others have to compromise in the use of compass to find the correct north direction.
The horizontal angle formed by an independently hanging rod magnet is called the position of that place. In this way, bowing from this inclination, horizon, is called magnetic kissing of that place. The salinity at the equator is zero and at the poles the salinity is 90 degrees.
Magnetism: All the above qualities of magnet are due to the state of magnet, it is called magnetism.
The region around a magnet, where the other magnet experiences attraction or repulsion force, is called the magnetic field of that magnet. The direction of the magnetic field is determined by the magnetic needle. The unit of magnetic field is gauss.
Magnetic field and current
In 1820, Danish scientist Orsted discovered a magnetic field around a conductor in which an electric current was flowing. He placed a magnetic needle near a conductor wire and saw that the direction of the needle remains parallel to the wire until there is no current flowing in the wire.
But as the current flows through the heat by pressing the key, the magnetic needle begins to deflect from its normal position. As the value of current in the wire increases, the deflection of the needle also increases. Thus, the experiment concludes that there is a magnetic field around a current carrying conductor.
The electric current produces a magnetic field. Electromagnets are made by this magnetic effect of electric current. To make an electromagnet, copper wire is wrapped around it with a piece of soft iron horseshoe rod. When an electric current is connected by connecting the ends of the wire to a battery, the umbilical rod becomes an electromagnet.
When the current in the wire is closed, the magnetic properties of the rod cease. There are many applications in the daily life of electromagnets. Electromagnet is used to remove iron pellets penetrated into the eyes, ears or any part of the body.
Electromagnets are also used in large factories to move heavy pieces of iron or steel from one place to another. Apart from this, electromagnets are also installed in many electrical appliances such as electrical bells, transformers etc.
A magnetic needle is used to determine direction. It always stays in the north-south direction. It has a small glass box, inside which a needle is placed. If we take full rotation of the Earth with a magnetic needle, the needle becomes perpendicular to the plane at two places on the ground plane, these places are called the Earth’s magnetic pole.
Type of magnet
Generally, some magnetic properties are found in substances. On the basis of this, substances can be divided into the following three parts-
- Anti-magnetic materials: Sub-magnetized materials are those materials that, when placed in the magnetic field, are magnetized in the opposite direction of the field. Examples of magnetized materials are zinc, bismuth, copper, silver, gold, diamond, salt, water, etc.
- Magnetic material: A magnetic material is a substance that, when placed in a magnetic field, is moderately magnetized in the direction of the field. Sodium, aluminum, manganese, copper chloride, etc. are examples of magnetic materials.
- Iron-magnetized materials: Iron-magnetized materials are those materials that, when placed in the magnetic field, are strongly magnetized in the direction of the field. Examples are iron, nickel, cobalt etc.
- Domain: The numerous, superfluous structures of atoms within ferromagnetic materials are called domains. A domain has atoms ranging from 1018 to 1021. The magnetic properties of ferromagnetic materials are due to the mutual replacement and rotation of these domains.
The electrical effect caused by friction is well known. After grooming dry hair with a hard rubber comb, it has been observed that it attracts very small pieces of paper. This is because after combing with dry hair, there is an electric charge in the comb.
Similarly, a pen made of plastic shows attraction effect when rubbed on the surface of a woolen coat. Rubbing also brings electric charge from clothes. The electric spark can be easily seen with the sound of night after dry day.
The electric charge produced by the rubbing of two different materials is called static electricity. According to the nature of these substances, on one of these comes the positive charge and the other on the negative charge.
For example, when rubbing a glass rod with silk cloth, there is a positive charge in the rod and an equal amount of negative charge in the silk cloth.
Rubbing the ebony rod with flannel brings an equal charge of negative charge and flannel in the ebony rod. There is mutual repulsion in similar charges and attraction in opposite charges.
Electrical induction by friction can be elucidated based on the transfer of electrons. When the glass rod is rubbed with silk, some of the electrons in the rod are transferred to the silk cloth, which causes an equal amount of negative charge in the silk textile due to the lack of electrons in the rod and the receipt of electrons.
By using a hollow conductor made of metal to charge it with static electricity, it has been found that the charge completely falls on the outer surface of the conductor and the internal surface is charged.
When the lightning falls on the car, the person sitting in it is protected from the impact of electricity because all the charge created by the lightning remains on the outer surface of the car and it can go into the ground due to the ground contact of the lower parts of the car. is.
When charged with a cone-shaped conductor, it is seen that the charge is higher at and near its pointed head, while relatively less at the spherical surface. If the impulse is increased on this conical conductor, the pointed head will not only cause charge corrosion but it is also a collector of charge. The tadit-driver is based on this principle.
Lightning is a large absorption process between two charged clouds or a charged cloud. Lightning-conductors are used to protect the high walls from lightning-breaking. In the lightning conductor a thick copper leaf is applied from the top of the building to the ground on the outer wall of the building.
This copper-leaf is installed upright on the roof of the building in the form of several pointed wires or tridents and the lower end near the ground is pressed to the bottom of the ground by connecting it with a copper plate. When the charged cloud passes over the atalica, the torrential conductor takes charge and makes it flow to the ground. In this way, the elevated building survives safely.