Capacitors

Discussion in 'Feedback and Suggestions' started by sridhar10chitta, Dec 2, 2005.

  1. sridhar10chitta

    Thread Starter New Member

    Dec 1, 2005
    3
    0
    I found the description of capacitors very interesting and comprehensive in http://www.ibiblio.org/obp/electricCircuits/DC/DC_13.html.

    Very few textbooks that I read have given such a detailed explanation on this topic.
    However, I found that the direction of current indicated in the figures titled "The Capacitor acts as a LOAD" and "The Capacitor acts a SOURCE" to be misleading.
    Further, the sentence "Note the direction of current with regard to the voltage polarity: " in the description does not serve as an explanation regarding this.
    I will be happy if you could provide more details on the directions of current in both the figures.

    Thanks
    Sridhar Chitta
    Assoc. Prof.
    Dept of Instrumentation and Control Engg
    Vignan Institute of technology and Science
    Deshmukhi Village, Pochampally Mandal
    Nalgonda Distt
    near Hyderabad - 508284
    Andhra Pradesh
    India
    Website: www.vignanits.ac.in
     
  2. Dcrunkilton

    E-book Co-ordinator

    Jul 31, 2004
    416
    11

    I think that there is a simple explanation. This series of books is based on electron flow. The currrent is considered to flow out the negative terminal of the source, such as a battery, through the load, returning to the positive terminal of the source. This is backwards from conventional current flow where the currrent flows out the positive terminal of the battery, through the load, returning to the negative terminal of the battery. Most texts are based on conventional current flow. In fact, all electrical engineering texts, that I have seen, are based on conventional current flow. That leaves some, if not most, of the "electronic technology" texts , for technicians rather than engineers, with the backwards electron flow. At least, it is backwards if you are an engineer. The electron flow method probably made the most sense back when we were still teaching vacuum tubes, also known as valves in the
    British Empire.

    I am accustomed to teaching it both ways, depending on the text. I once explained to my new students that since we were technicians that we would be using electron flow. A day later the new instructor (me) found out that one of our texts used conventional current flow. I think that we tried to teach that one "electron flow" in spite of the one text.

    For more on this, see Volume I - DC -> Chapter 1: BASIC CONCEPTS OF ELECTRICITY -> Conventional versus electron flow here

    Tony Kuphald, the original author, said in response to a request for a conventional current flow version of the book that he did not think it was feasible to support two versions of the book. Some publishers make available both versions of a text for electronic technology courses.

    The direction of the arrows makes sense to me for electron flow, but looks backwards for conventional current flow.

    Dennis Drunkilton
     
  3. sridhar10chitta

    Thread Starter New Member

    Dec 1, 2005
    3
    0
    Thanks for the detailed explanation.
    I think it would be appropriate if the sentence is modified to read as "Note the direction of electron current with regard to the voltage polarity".
    The historical perspective that you have given was useful and I have conveyed this to my staff members and they were happy and satisfied with the explanation.
    Regards
    Sridhar


     
  4. Dcrunkilton

    E-book Co-ordinator

    Jul 31, 2004
    416
    11
    I have made the change to text which you have suggested. It is in the master copy at ibiblio/kuphaldt. I have added you to the contributors list at the end of volume 1.

    Thanks for the input

    Dennis Crunkilton
     
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