Two Important Contributions to Electromagnetism

Electromagnetism is a branch of Physics in which the electromagnetic force is studied. The study involves the interaction between the electrically charged particles. The charged particles have electromagnetic force between them, and it is a combination of electrical and magnetic forces. The electromagnetic force is one of the four fundamental forces.

In this article, we shall try to understand how the special theory of relativity and the Lorentz force is related to electromagnetism.

What is the Special Theory of Relativity?

The special theory of relativity is also known as special relativity. It is the physical theory which states the relationship between space and time. There are two postulates on which the special theory of relativity is based:

  • Laws of Physics are invariant.
  • The speed of light in a vacuum is the same as in any other space, and it is not dependent on the light source.

Relation Between The Relativity And Unifying Electromagnetism

During the theoretical investigation, wave propagation was discovered. It was a part of classical electromagnetism. A branch of theoretical physics that deals with the synergy between the electric charges and the current are known as classical electromagnetism. This study is done using the classical Newtonian model. With the help of this theory, one can understand how electromagnetic phenomena behave when the field strength and relevant length scales are large enough such that the quantum mechanical effects are negligible. This study also helped in the further development of the special theory of relativity.

What is Lorentz Force?

Lorentz’s force is defined as the combination of the magnetic and electric force on a point charge due to the electromagnetic field. The following are the two formulas of Lorentz force when there is a charged particle and a continuous charge distribution.

Lorentz Force for the Charged Particle



  • F is the force acting on the particle
  • q is the electric charge of the particle
  • v is the velocity
  • E is the external electric field
  • B is the magnetic field

Lorentz Force for the Continuous Charge Distribution



  • dF is the force on a small piece of the charge
  • dq is the charge of a small piece

The importance of Lorentz force is that it explains the mathematical equations and the physical importance of the forces acting on the charged particles that travel through space. This space consists of an electrical field and a magnetic field.