In the entire field of Electrical Engineering, there is a consensus to use "j" instead of "i" for the imaginary axis, because "i" in all its shapes and forms (upper case, lower, with subscript that's either upper, lower) is used to refer to electrical current and all the types signal components it can be decomposed into.
Not sure how relevant this is for others, but in the day to day life of an electrical engineer it is much more common to work with complex currents, voltages, powers, rather than real ones. Every now and then I have to be reminded that "i" was used originally :P
j - can also be the unit of the imaginary axis.
In the entire field of Electrical Engineering, there is a consensus to use "j" instead of "i" for the imaginary axis, because "i" in all its shapes and forms (upper case, lower, with subscript that's either upper, lower) is used to refer to electrical current and all the types signal components it can be decomposed into.
Not sure how relevant this is for others, but in the day to day life of an electrical engineer it is much more common to work with complex currents, voltages, powers, rather than real ones. Every now and then I have to be reminded that "i" was used originally :P