Help on Electronics with Mathmatics

Discussion in 'Homework Help' started by tklesel, Jan 18, 2006.

  1. tklesel

    Thread Starter New Member

    Jan 18, 2006
    question #1

    which of the following transmission lines may be classified as an "electrically long" line
    a. any line more than one quarter mile lone
    b. any line having distributed capacitance
    c. a 30 foot line operated at 300 kilohertz
    d. a 300 mile line operated at 30 hertz
    e. a 30 inch line operated at 300 megahertz

    question #2

    a transmission of even-numbered harmonic frequencies may be minimized by placing accross the transmission line a
    a. half wave shorted stub
    b/ quarter wave open stub
    c. quarter wave shorted stub
    d. half wave open stub
    e. full wave open stub

    if any one can help it would be great and if you find the answer, where did you locate them

  2. spork891

    New Member

    Jan 17, 2006
    Question 1:

    I'd say the 30 inch line is a pretty good candidate. 300Mhz is awfully fast for a transmission line that long.

    A and B are definitely wrong, and D is probably wrong as well. C is sort of a toss up IMO, someone else may like to weigh in.

    I just happen to know this because I've taken an EM course, which is what it looks like you're in the middle of.

    question #2

    Don't really know much about filtering out even numbered harmonics with stubs.

  3. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    In question number one, you can throw out any answer that doesn't specify a frequency.

    Those with a frequency, find out the wavelength and then divide the length of line by the wavelength. The largest value is the answer.

    In the second question, look for the current and voltage distribution about a wavelength. You will be looking for a way to minimize the signal.

    Those answers can be found in NEETS module 10. visit to get a copy.
  4. tklesel

    Thread Starter New Member

    Jan 18, 2006