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In the previous sections, we have learned that electromagnetic force is carried by electromagnetic fields that comprise electric and magnetic fields. In this session, we are going to learn about magnetic fields in detail.
What are Magnetic fields?

A magnetic field is an area around moving electric charges, electric currents, or magnetic materials within which the force of magnetism acts.
It can be represented by "B", and the unit is Tesla.
Magnetic field
A magnetic field is a vector field that specifies the magnetic impact on moving electric charges, electric currents, and magnetic materials.

Bar magnet with magnetic fields

A moving charge in a magnetic field undergoes a force perpendicular to its velocity and the magnetic field.
Magnetic fields are created by moving electric charges and the intrinsic magnetic moments of elementary particles connected with a fundamental quantum property, and spin of the particles.
Magnetic and electric fields are interrelated, and both are the elements of the electromagnetic force, which is one of the four primary forces of nature.
Primary forces of nature

Magnetic fields are used in almost all modern technology, especially in electrical engineering and electro mechanics.
Rotating magnetic fields
Rotating magnetic fields are generally used in electromechanical applications such as electric motors and generators. The influence of magnetic fields in electric devices such as transformers is formulated and examined as magnetic circuits.
Magnetic field lines:
Magnetic field lines are a visual tool used to represent magnetic fields. They describe the direction of the magnetic force on a North monopole at any given position.
Properties of magnetic field lines:
  • Magnetic field lines never intersect each other.
  • The density of the field lines shows the strength of the field.
  • Magnetic field lines always make closed-loops.
  • Magnetic field lines always emerge from the north pole and terminate at the south pole.