Electromagnetic force


Electromagnetic force is one of the four fundamental forces that manifests as a unification of electrostatic force and the magnetic force. Electromagnetic force arises from the interaction of electromagnetic field, which is simply a unification of electric field and magnetic field of the charged particles, exchanging virtual photons. The electromagnetic force is what we experience the most of the time in our life, the other one being gravity. From radio waves to the visible light and gamma rays, everything is an electromagnetic wave. Similar to the gravitational field, the electromagnetic field has an infinite range and the strength of the electromagnetic field is inversely proportional to the distance from the source.

Frequently Asked Questionsedit

Are electric and magnetic fields different?edit

The electric field and magnetic field was first thought and explained as two separate fields. Any particle that has an electric charge in this universe has an electric field extending to infinity. Electron being the most common charged particle has an electric field. When electrons move in a straight line or a loop, we observe that it produces a magnetic field around it. This is generally known as Ampère's law. In a coil, the flow of electrons gets more interesting as the magnetic field formed resembles a field around a bar magnet. Similarly, when a magnetic particle with an associated magnetic field is moved or changed, it produces an electric field. This is generally known as Faraday's law. It is only after James Clerk Maxwell had published the Maxwell's equations, the two forces were unified. Later, with Albert Einstein's special relativity, the electromagnetism is proved, explaining that electric and magnetic fields are simply the result of the exchange of photons when a charge-carrying particle like the electron or a magnetic dipole move and interact with each other.

Why moving a charge creates a magnetic field?edit

The magnetic field created by moving charged particles can be explained with special relativity and Coulomb’s law. In simpler words, a magnetic field is something that is observed only in our frame of reference. In the frame of reference of the moving charge particles, the magnetic fields are only a result of relative motion and are the effects of special relativity of length contraction that results in an electrostatic force.

For example, consider a current carrying wire. If we introduce a magnetic compass or a charged particle next to the wire, it will be deflected. From our frame of reference, the electrons are moving relative to us, and we perceive the deflection as an effect due to the influence of a field called magnetic field. But if we were to move along the electrons, it is the nuclei of the wire material that are moving relative to us and the electrons. And due to the results of the relative motion, the nuclei appears to contract in length, and this creates an increased positive electric flux, which means a net charge is formed. In this frame of reference, we perceive nothing but an electrostatic repulsion, rather than a magnetic field. So it is clearly a single electromagnetic force manifesting itself as a component of the electric field as observed in one frame of reference and as a component of the magnetic field observed in the other.