The magnetic field is a vector quantity that describes the interaction between magnetic bodies and moving electric charges (electric currents). A moving electric charge in a magnetic field encounters a force perpendicular to its velocity and magnetic field components. A permanent magnet’s magnetic field attracts ferromagnetic substances like iron. Apart from this interaction, a magnetic field that changes with location will apply a force to some non-magnetic substances by influencing the movement of their outer atomic electrons. Magnetic fields envelop magnetised materials that are produced by electric currents, such as those employed in electromagnets (by varying electric fields). As both the direction and strength of a magnetic field may change with position, it is represented mathematically by a function allocating a vector to each point called a vector field.
Magnetic fields are generated by electric current and the elementary particles’ intrinsic magnetic moment associated with a basic quantum characteristic, “spin”. Electric fields and magnetic fields are mutually connected. They are both the fundamental components of electromagnetic force (one of the four primary forces in physics).
Magnetic fields can be illustrated by using continuous force lines of magnetic flux that emanate from north-pointing magnetic poles and enter south-pointing magnetic poles. The line density represents the magnitude of the magnetic field. Field lines are crowded together at the poles as magnetic fields are denser there. Equally divided parallel straight lines denote a uniform magnetic field. The flux’s direction is the direction in which the north-pointing pole of a tiny magnet points. The flux lines are continuous, resulting in closed loops. In the case of a bar magnet, they rise from the north-pointing pole and enter the magnet at the south-pointing pole. Those flux lines then continue piercing through the magnet to the north pole, which pops up again. The weber is the SI unit of magnetic flux. The number of webers is defined as the measure of the number of field lines that pass a given area.
The Video Explains the Basic Concepts of Magnetic Fields
Magnetic fields can be denoted mathematically by elements called vectors that have magnitude as well as direction. Two types of vectors are in use to represent a magnetic field. One is called magnetic flux density (magnetic induction), denoted by the symbol ‘B’. The other component is magnetic field strength (magnetic field intensity), denoted by the symbol ‘H’. The magnetic field H can be considered as the magnetic field generated by the current flow in wires and magnetic field B as the aggregate magnetic field, including the contribution by the magnetic properties of the substances in the field. When a current travels through a wire wrapped around a soft-iron cylinder, the field H is very weak. However, the actual average field B within the iron could be thousands of times more powerful because B is largely enhanced by the orientation of the iron’s myriad small natural atomic magnets in the same direction of the field.
The term “magnetic field” is employed for two distinct and closely related vector fields, represented by symbols B and H. Magnetic field strength H is calculated in the SI base units of A/m (ampere per meter). Magnetic flux density B is calculated in tesla (newton per meter per ampere). B and H vary in how they are responsible for magnetisation. In a vacuum, the two magnetic field components are associated with vacuum permeability. In the case of a magnetised material, the quantities differ by the material’s magnetisation at each point.
Magnetic fields are used in electromechanics and electrical engineering. Rotating magnetic fields are applied in both electric generators and motors. The interplay of magnetic fields in electric equipment like transformers is designed and tested as magnetic circuits. Magnetic forces show information about the charge carriers in a body through the Hall effect. The Earth creates its own magnetic field that protects the Earth’s atmosphere from the solar winds.
Important Magnetic Field Questions with Answers
1) What is meant by a magnetic field?
The magnetic field is a vector quantity that describes the interaction between magnetic bodies and moving electric charges (electric currents). A moving electric charge in a magnetic field encounters a force perpendicular to its velocity and magnetic field components. A permanent magnet’s magnetic field attracts ferromagnetic substances like iron. Apart from this interaction, a magnetic field that changes with location will apply a force to some non-magnetic substances by influencing the movement of their outer atomic electrons. Magnetic fields envelop magnetised materials that are produced by electric currents, such as those employed in electromagnets (by varying electric fields). As both the direction and strength of a magnetic field may change with position, it is represented mathematically by a function allocating a vector to each point called a vector field.
2) How are magnetic fields generated?
Magnetic fields are generated by electric current and the elementary particles’ intrinsic magnetic moment associated with a basic quantum characteristic, “spin”. Electric fields and magnetic fields are mutually connected. They are both the fundamental components of electromagnetic force (one of the four primary forces in physics).
3) How are magnetic fields represented?
Magnetic fields can be illustrated by using continuous force lines of magnetic flux that emanate from north-pointing magnetic poles and enter south-pointing magnetic poles. The line density represents the magnitude of the magnetic field. Field lines are crowded together at the poles as magnetic fields are denser there. Equally divided parallel straight lines denote a uniform magnetic field. The flux’s direction is the direction in which the north-pointing pole of a tiny magnet points. The flux lines are continuous, resulting in closed loops.
4) Explain the magnetic field lines of a bar magnet.
In the case of a bar magnet, they rise from the north-pointing pole and enter the magnet at the south-pointing pole. Those flux lines then continue piercing through the magnet to the north pole, which pops up again.
5) What is the SI unit of magnetic flux?
The weber is the SI unit of magnetic flux. The number of webers is defined as the measure of the number of field lines that pass a given area.
6) Explain the components of magnetic fields.
Magnetic fields can be denoted mathematically by elements called vectors that have magnitude as well as direction. Two types of vectors are in use to represent a magnetic field. One is called magnetic flux density (magnetic induction), denoted by the symbol ‘B’. The other component is magnetic field strength (magnetic field intensity), denoted by the symbol ‘H’. The magnetic field H can be considered as the magnetic field generated by the current flow in wires and magnetic field B as the aggregate magnetic field, including the contribution by the magnetic properties of the substances in the field.
7) What is the unit of magnetic field strength H?
Magnetic field strength H is calculated in the SI base units of A/m (ampere per meter).
8) What is the unit of magnetic flux density B?
Magnetic flux density B is calculated in tesla (newton per meter per ampere). B and H vary in how they are responsible for magnetisation.
9) What are the uses of magnetic fields?
Magnetic fields are used in electromechanics and electrical engineering. Rotating magnetic fields are applied in both electric generators and motors. The interplay of magnetic fields in electric equipment like transformers is designed and tested as magnetic circuits. Magnetic forces show information about the charge carriers in a body through the Hall effect. The Earth creates its own magnetic field that protects the Earth’s atmosphere from the solar winds.
10) In a vacuum, the two magnetic field components are associated with vacuum ______.
Answer: permeability
Explanation: In a vacuum, the two magnetic field components are associated with vacuum permeability.
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Practice Questions
1) What is a permanent magnet?
2) What is a temporary magnet?
3) What is a vector field?
4) What is the difference between a magnetic field and an electric field?
5) What are the two vector components that represent a magnetic field?
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