Electrical technology is mainly composed of circuit theory and electrical appliances. When solving problems with equations in circuit theory, the directions of voltage and current must be assumed. It should be a direction, but it is artificially described as a "reference direction" and seems to be a "benchmark". The word "reference direction" originally originated from foreign reference direction, and it has been copied mechanically in translation, and the result has always been harmful. It is easy to judge the assumed direction of resistance voltage and current and their correlation, but it is difficult to judge capacitance and inductance, especially the negative sign subjectively added in front of inductive voltage. I don't know how many people have been taken down!
Magnetic circuit is more difficult than electric circuit. When it's the turn to talk about motors, at present, no matter how much or how little the actual magnetic leakage is, all books should talk about magnetic leakage. It seems that there is no book without magnetic flux leakage, and the author is on cloud nine, and the readers are at a loss.
Electronic technology is mainly amplifier. The purpose of setting the operating point of the amplifier is to obtain the maximum distortion-free output voltage amplitude at first. As a result, I don't know how many pages I spent with the current smelly graphic method, and I didn't even have a few volts.
Both electron tubes and amplifiers have the first parameter. In fact, all the electrician e-books are paying attention to him now. For example, transistors do not talk about beta values in amplifier applications, and power amplifiers do not talk about power amplifiers. In short, the author doesn't know what he is shouting, and it's strange that the reader doesn't step into the maze.
The real reason is that the history of electrician and electronics is short and the theory is immature.
As readers, we should realize the defects of this book now and not be fooled. As an author, it is necessary to increase investment and learn the theory of electrical and electronic engineering.