Electromagnetic Force Homework Help, Assignment Help, Online Tutor, Tutoring

Submit Assignment

* *

Payment Online Assignment Help

Homework Help

sfsf

Electromagnetic Force

The electromagnetic force is the force that acts between charged particles. The first law of electro-magnetism is the Coulomb’s law of electric force between two charges q₁ and q₂ fixed (i.e. kept at rest) at relative distance r₁₂. The Coulomb’s law states that the electric force between these static charges is given by

Note that the above law is similar in form to the law of gravitation. The constant of proportionality = 9 × 10⁹ Nm/C². However, the electric force is either repulsive or attractive depending whether the two charges are like or unlike.

Space-Time Structure, Newton’s Laws and Galilean Transformation

If the charges are moving then, besides electric force, there also acts a magnetic force on each charge. Magnetic force is velocity dependent and acts in a direction perpendicular to the velocity of the particle.

Electro-magnetic forces are responsible for the structures of atoms, molecules and aggregates of molecules. Electrons interact with a nucleus through electro-magnetic forces to produce and atom; atoms interact with other atoms through electro-magnetic forces to produce molecules; molecules interact with other molecules through electro-magnetic forces to produce bulk matter. (Of course, one must not forget that an atomic and molecular levels, Newtonian mechanics does not work; we use quantum mechanics along with electro-magnetism to explain the dynamics of these objects.)

The importance of electro-magnetic forces in Newtonian mechanics lies in the fact that all large scale’ contact forces’ arise primarily from electro-magnetic interactions between molecules of the bodies in contact. By contact force, we mean a force which arises when two bodies are in physical contact, like forces of fiction, viscosity, tension in strings etc. In fact, all familiar forces of mechanical nature are contact forces.

Contact forces are large scale effect of inter-molecular forces acting mostly between electrically neutral systems-atoms and molecules. All molecules, including electrically neutral and non-polar ones, interact with each other including a short-range Van der Waals force which falls off as 1/r², where r is the distance between two molecules. The basis of Van der Waals force is electro-magnetic interaction (and quantum dynamics). When two bodies are brought in contact, it is these forces between molecules of two bodies that manifest on large scale as forces of friction etc.