what is electromagnetic transients and what are the causes of electromagnetic transient?

Question

answers can be in a specific application such as transmission line etc.

Answer 1

Because you use the term "electromagnetic," I imagine you're referring to transient pulse (as opposed to continuous waves) propagating through space. Then you mention "transmission line" which implies you're really interested in electrical transients which propagate along the length of a wire, as in a power distribution system. Then again, "transmission line" often refers to the coaxial cable between a radio transmitter and its antenna, which can have a third type of transient. I suspect you don't really understand what you're asking. Quit screwing around on the Internet and go find a real electrical/electronic engineering textbook that addresses your specific interest. Be prepared for some serious calculus, vector and tensor math, and many differential equations. Transient analysis is one of the deepest subjects in electrical engineering. Practical solutions often depend on trial and error and often seem almost "magical."

Answer 2

I would like to remark that there are no physical magnitudes of value infinity.
So going to transmission lines ,the have self induction and capacity

If there is a change from one state to another the change of current in the self can´t be instantaneously because the voltage drop is=
L di/dt and if the current would change in dt=0 di would be finite and the voltage drop would become infinite.

The same thing happens with a capacitor i=Cdv/dt.If there were a

finite voltage change in zero time the current through the capacitor would become infinite

So the change from one state to another occurs in a finite time
and the variation of the magnitudes involved( always finite values)
is the electromagnetic transient

Answer 3

The result of switching