Electromagnetism and charged particles in motion

[toumaza]

Whenever a charged particle is in motion ,there is both electric and magnetic fields created. Why is it that we only study one of it at a time ?

 

[jtbell]

Historical inertia. Electric and magnetic forces were originally discovered in different phenomena.

 

[Nugatory]

Why is it that we only study one of it at a time ?

Some of it just convenience in learning. Students have to start somewhere, and the easiest problems are the ones in which only one of the two fields appear. Once the student has a solid grasp of these, they're ready to move on to more advanced problems in which both fields are present and treated as a single electromagnetic field.