A Conversation for Complex Numbers - an Introduction

Electrical Engineers call it j not i

Post 1


Takes me back to when I was studying electrical engineering quite a few years ago. the letter i is reserved for current so we electrical engineers call it j not i.

it's very useful for carrying out calculations on inductive and capacitive circuits where the resistance is the real part and the inductance is -j & capacitance is +j (inductive current lags the resistive current by almost 90 degrees & vice versa for capacitive.

We also generally convert it to polar coordinates which simplifies multiplication and division if my memory serves me well.

Electrical Engineers call it j not i

Post 2

Gnomon - time to move on

..but makes addition and subtraction much harder.smiley - smiley

Electrical Engineers call it j not i

Post 3

Icy North

Hi highamexpat,

I too studied electrical engineering many years ago - so long in fact, that I forgot to mention this. Many thanks for posting it here!

Those co-ordinate systems always confuse the hell out of me. Did you use those Smith charts, which we plotted things on? If I had some now, I'd give them to my daughter to colour in.

smiley - cheers Icy

Electrical Engineers call it j not i

Post 4


Hi icy

I never had much problem with with Argand diagrams or complex numbers though Calculus was another story.

I found a great calculator which let you input in the form a+jb & it would do any calculation you wanted & switch between cartesian or polar coordinates at the push of a button.

Never had anything to do with Smith diagrams (that I can remember) the worst ones were those logic charts for Boolean algebra. i could never get my head round them.

Cheers highamexpat

Electrical Engineers call it j not i

Post 5



This conversation brings back memories, I spent an age racking my brain over this then I to discovered that calculator.

Key: Complain about this post

Electrical Engineers call it j not i

Write an Entry

"The Hitchhiker's Guide to the Galaxy is a wholly remarkable book. It has been compiled and recompiled many times and under many different editorships. It contains contributions from countless numbers of travellers and researchers."

Write an entry
Read more