Last updated on Monday, June 5th, 2023

Lorentz Force was defined by the Dutch physicist Prof. Hendrik Antoon Lorentz who lived from 18/07/1853 to 4/02/1928. His research contribution mainly focused on constructing a theory to understand the relationship between electricity, magnetism, and light.

Deep Side information of Lorentz Force

Nobel Prize was given to Prof Lorentz and his pupil Zeeman in 1902. Because Prof. Lorentz observed and explained that electrons (charged particles) within the atom also oscillate (transition from one state to the other) and release light (photons). Actually, sometime before it, Prof. Maxwell showed that oscillations of the electric charge produced electromagnetic radiation (Electric and Magnetic Fields move together). Now, Prof. Lorentz, thought if it is true, then the external magnetic field will also affect the oscillation of the charged particle (electron) inside the atom. Hence, a change in the wavelength is observed. This idea was implemented by his pupil Zeeman in 1896 and observed perfectly true. Which is known as the Zeeman effect nowadays and they awarded a Nobel prize for this discovery.

What is a Lorentz Force?

If a charged particle is moving or placed in the electric and magnetic field a joint force is exerted on it,  which is known as Lorentz force. On the other side, you can say, this force is a combination of electric force and magnetic force on the charged particle.

Lorentz Force Formula

In this formula, the first part is the electric force on the charged particle and the second one is the magnetic force.

q= electric charge on the particle

E= Electric field

B= Magnetic Field

v= velocity of the charged particle.

Electric force direction:

same as the electric field direction,

Magnetic Force Direction:

Perpendicular to the plane of v and B. If v and B are along the X and Y-directions then magnetic force will be in Z-direction which is perpendicular to both.

Analysis of Formula

If suppose an electric charge particle moves inside the electromagnetic field, then the electric force and magnetic force will be opposite to each other. By varying the magnitude of the electric and magnetic fields the magnitude of both forces can be equal. In this case, the Lorentz force will be zero, experienced by the charged particle.

qE= qvB

E=vB

or v= E/B

Question: Can you explain why the electric and magnetic forces will be opposite to each other in a uniform electromagnetic field?

Answer: Suppose the electric field and magnetic fields are along x and y-directions respectively and the particle is moving along the z-direction. As you know that electric force direction will be towards the electric field direction. So Electric force direction is along the X-direction.

Now the charged particle is moving along the z-direction and a magnetic field is in Y-direction. The magnetic force direction can be defined by Fleming’s left-hand rule, which will be perpendicular to the v and B (means y and z-axis) and opposite to the x-direction.

That is why in opposite direction to the electric force, and if equal in magnitude then it will be zero. As explained above.

Question: What is the unit of the magnetic field in the CGS system?

Answer: Gauss

1 Tesla = 10⁴ Gauss

SI unit of the magnetic field is = Newton Ampere^-1meter^-1 

1 Tesla=  1 Newton Ampere^-1meter^-1