What kind of switch can break the circuit if an electrical signal came into the switch ?

I am looking for some sort of "electronic switch" rather than mechanical switch .... so I do not have to break the circuit by moving the switch button , instead only a small electrical signal enter to the switch (through some wire) can cause the switch to break the circuit .... is there a switch that can... show more I am looking for some sort of "electronic switch" rather than mechanical switch .... so I do not have to break the circuit by moving the switch button , instead only a small electrical signal enter to the switch (through some wire) can cause the switch to break the circuit ....
is there a switch that can break the circuit at some current (this is present so far BUT ALSO : ) AND return back when the currency change by itself ???
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