Fantastic wealth of information, well presented. I've enjoyed reading your course and have used it for review and learning many times. Thank you. I believe I've noticed a miss-print in Chapter 5, Reactance and Impedance-R, L, and C. Starting on page 103 of the "Lessons In Electric Circuits, Volume II - AC ", Sixth Edition and again in the newer version, the imaginary portion of the current in the series circuit under evaluation for this lesson is misrepresented with the "j" portion of the expression, missing. The expression is written in the book " 12.589m + 76.708m " but , I believe, should read, " 12.589m + j76.708m ". The error is repeated thru out the example.