Magnetism
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Dear Readers, Here we have given the list of Important Facts of Magnetism for competitive Exams. General Science is very important Topic for competitive Examination. In this topic, we have given about the Physics Magnetism, substance, method, definition & types. Candidates those who are preparing for the exams make use of it.
Important Facts of Magnetism
A physical phenomenon produced by the motion of electric charge, which results in attractive and repulsive forces between objects.
Discover Magnet:
The word magnet comes from the Greek “magnítis líthos”, which means “Magnesian Stone”. Magnesia is an area in Greece (Now Manisa, Turkey) where deposits of magnetite have been discovered since antiquity.
Property:
| S.No | Properties Of Magnetism |
|---|---|
| 1 | Magnets attract objects of iron, cobalt and nickel. |
| 2 | The force of attraction of a magnet is greater at its poles than in the middle. |
| 3 | Like poles of two magnets repel each other. |
| 4 | Opposite poles of two magnets attracts each other. |
| 5 | If a bar magnet is suspended by a thread and if it is free to rotate, its South Pole will move towards the North Pole of the earth and vice versa. |
Magnet Uses:
- Magnets are used to make a tight seal on the doors to refrigerators and freezers.
- They power speakers in stereos, earphones, and televisions.
- Magnets are used to store data in computers, and are important in scanning machines called MRIs (magnetic resonance imagers), which doctors use to look inside people’s bodies
Magnetic Substance:
There are three magnetic substances.There are
| Magnetic Substance | Definition | Example | Magneic Field | Temperaure |
|---|---|---|---|---|
| Paramagnet | Feebly magnetised in the direction of the magnetic field when placed in the strong magnetic field. | Aluminium, Platinum, salts of iron | Strong | Increase |
| Diamagnet | Feebly magnetised in the oppositedirection of the magnetic field when placed in the strong magnetic field. | Gold, Silver, Zinc, copper | Weak | No Change |
| Ferromagnet | Substances which are strongly magnetised in he diection of the magnetic field when placed in it | Iron,nickel, cobalt | Strong | Increase |
Making of Magnet Method:
(1) Single touch method
(2) Double touch method
(3) Using electric current.
Important Terms In Magnetism & Definitions:
| Important Words | Definitions |
|---|---|
| Magnetism | it is a property of certain substances which pull closer or repel other objects. |
| Magnetic fields | Magnetic fields are produced by electric currents, which can be macroscopic currents in wires, or microscopic currents associated with electrons in atomic orbits. |
| Electromagnetism | An interaction between electricity and magnetism, as when an electric current or a changing electric field generates a magnetic field, or when a changing magnetic field generates an electric field. |
| Magnetic Energy | The potential energy of a magnet of magnetic moment, m, in a magnetic field, B, is defined as the mechanical work of magnetic force on re-alignment of the vector of the Magnetic dipole moment, and is equal |
| ElectroMagnet | An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. Electromagnets usually consist of wire wound into a coil. |
| Magnetic Flux | magnetic flux in an area taken perpendicular to the magnetic flux's direction. |
| Magnetic flux density | Magnetic flux density is defined as the amount of magnetic flux in an area taken perpendicular to the magnetic flux's direction |
| Flux density | F lux density is a measure of the force applied to a particle by the magnetic field. |
| Electric Flux Density | A measure of the intensity of an electric field generated by a free electric charge, corresponding to the number of electric field lines passing through a given area. |
| Magnetic Field Strength | The amount of magnetizing force (how much force it has to magnetize, magnetic materials such as iron, steel, etc) is called Magnetic field strength which is denoted by (H). |
Important to Know About Magnetism:
1) magnetism from the Earth’s magnetic field
2) magnetism produced through metabolism within the cells in the body.
Types of Magnetism:
| S.No | Types Of Magnets | Examples | Explanation |
|---|---|---|---|
| 1 | Temporary | Iron alloy | It can be easily magnetized by even a weak magnetic field. |
| 2 | Permanent | A Horseshoe magnet, a refrigerator magnet, a freezer seal | Once they are magnetized, these objects do not easily lose their magnetism |
| 3 | Electromagnets | hard disk drives, speakers, motors, and generators | These are used when a very strong magnet is necessary.The Core act as a strong magnetic field |
Magnetic Field & Range:
| Typical magnetic fields | Tesla Range |
|---|---|
| Inside Atomic Nuclei | 10 11 T |
| Superconducting Solenoids | 20 T |
| Superconducting Coil Cyclotron | 5 T |
| Small Ceramic Magnet | 0.1 T |
| Earth's field at the equator | 4(10 −5 ) T |
| Interstellar Space | 2(10 −10 ) T |
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