[InterceptPoint]

SQRT(-1) is “j” in electrical engineering because “i” means something else entirely. It means the same thing in physics, but physicists manage to handle the ambiguity.
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Well I could beg off on a $money is closer to math than engineering argument. But I won’t.

You are absolutely right. The Square Root of Minus 1 is in universal use in the engineering work, at least electrical engineering.

But I should be forgiven since in my third grade complex algebra class we always used i. It’s hard to break old habits. 😎😎😎😎

[NorthMountain]

My educational and professional experience spans physics, mathematics and engineering. Physics and Maths use "i" for "imaginary", EE uses "j" to avoid confusion with "i" for current. At least, I think that's why they (we?) use "j". As you note, SQRT(-1) cannot be avoided in EM field theory, or control theory, or a host of other things.

So there's no problem with your complex algebra class or your use of the terminology learnt therein. You're just speaking mathematician-ese.