Difference Between Electrostatic and Electromagnetic Force

Main Difference – Electrostatic vs. Electromagnetic Force

Electricity and magnetism are a key part of modern life, and they are key subject areas in physics. Electric and magnetic fields are closely related and they interact with each other. The terms “electrostatic force” and “electromagnetic force” refer to these interactions. The main difference between electrostatic and electromagnetic force is that electrostatic forces refer to the forces between charges which are not moving relative to each other whereas, electromagnetic force refers to electrostatic forces as well as other forces between charges and magnetic fields where they may be moving relative to each other.

What is Electrostatic Force

Electrostatic force refers to forces between static electric charges. The electrostatic force $F$ between two objects with charges $q_1$ and $q_2$ separated by a distance $r$ between them is given by Coulomb’s law:

$F=\frac{q_1q_2}{4\pi {\varepsilon}_0{r}^2}$

The force is attractive if the two objects have opposite charges (positive and negative). If both the objects have the same types of charge, the force would be repulsive.

What is Electromagnetic Force

Moving charges create magnetic fields, and therefore, moving charges in magnetic fields experience force. If two charges move in each others’ vicinity, then they can exert forces on each other due to their magnetic properties. Electromagnetic forces are a superset which contains electrostatic forces in it. In addition to electrostatic forces, electromagnetic forces also consist of forces between stationary magnets, forces exerted between moving charges, and forces between charges and magnetic fields when there is relative motion between them. Note that electromagnetic forces specifically refer to electromagnetic interactions, which consist of an exchange of photons between different objects. This excludes any interaction that takes place between charged particles as a result of any of the other fundamental forces.

The relationship between electricity and magnetism is the idea behind electromagnets. These are magnets produced by passing electric currents around coils of wire. We can change the shape of wiring in order to create magnetic fields with different shapes. The idea is used to run maglev trains: electromagnets are created so that they can magnetically attract a train from the front while repelling it from behind. The magnets also repel the body of the train, so that it is effectively levitating above the track. This means they do not experience any friction from the tracks like ordinary trains do. As a result, they can travel much faster.

The relationship between electricity and magnetism is what allows us to run maglev trains.

Difference Between Electrostatic and Electromagnetic Force

Terminology

Electrostatic forces refer to forces between electric charges which are not moving relative to each other.

Electromagnetic forces describe any interaction that takes place due to, at a fundamental level, an exchange of photons. Electromagnetic forces include electrostatic forces.

Image Courtesy

“Shanghai Maglev” by Tim Adams (Own work) [CC BY 2.0], via flickr