Testing Book for Coaxial cable problem in Physics GRE

[rar0308]

Book for Coaxial cable impedance problem in Physics GRE

This is GR9277, Problem 18.
Is this covered in any physics undergraduate course?
What subject is this problem belong to?
What book do you recommend for studying this?

How can I make the picture appear bigger?

 

[Nabeshin]

Any electromagnetism course should cover this.

 

[rar0308]

Can you give a specific reference? I searched Griffiths' book but didn't find characteristic impedance thing.

 

[jasonRF]

a coaxial cable is an example of a transmission line. But more generally, the question is about wave impedance and impedance matching. I first learned about this topic in 3rd semester physics; the texts were "electromagnetic vibrations, waves, and radiation" by Bekefi and Barrett, and "the physics of vibrations and waves" by Pain. Bekefi is an excellent intro to electrodynamics and is by far the better of those books in just about every possible way. Higher level treatments are of course available - I am an electrical engineer and can say that almost all upper division "engineering electromagnetics" type of books cover this stuff in gory detail. It is useful so it is nice to see the GRE asking folks to connect EM to the practical world.

My guess is that a basic discussion is all that you need. Try googling "transmission line impedance match" and you will find lots of links. If you have access to a university library you should find many books that cover this. You likely don't need to acquire a book just for this topic.

A free book that covers way more than you might want (and so much that it may not be an efficient use of your time at this point) is at:
http://www.ece.rutgers.edu/~orfanidi/ewa/

jason

 

[Nabeshin]

Can you give a specific reference? I searched Griffiths' book but didn't find characteristic impedance thing.

Given that Griffiths devotes only 6 pages to waveguides (!), I suppose this question is meant by the GRE people to be more of a 'special topics' featuring EE rather than an E&M question.

(Upon closer examination, even Jackson doesn't cover this! I suppose I was lucky to get this in my course based on Heald and Marion's book)

 

[Lavabug]

Read the relevant chapter(s) in Cheng's book (fundamentals of engineering EM or something to that avail). I covered this stuff in my 2nd EM course and in one of my labs.

 

[jasonRF]

Given that Griffiths devotes only 6 pages to waveguides (!), I suppose this question is meant by the GRE people to be more of a 'special topics' featuring EE rather than an E&M question.

(Upon closer examination, even Jackson doesn't cover this! I suppose I was lucky to get this in my course based on Heald and Marion's book)

I think it is too bad that it might be considered outside the scope of physics; I would think quite a few pure physics experiments require RF electronics that need to be impedance matched in order to provide usable experimental results. Or perhaps it is just that many of the upper division books/courses were developed with the assumption that students take an intro level course on waves that includes the topic of transmission lines and impedance matching. I just know that I had to take such an intro course along side the pure physics majors, but have no idea how common that is these days.

I just found an online book from such a course that may suit the OP just perfect:

http://farside.ph.utexas.edu/teaching/315/Waveshtml/index.html

The sections on transmission lines look good at a first glance.

jason

EDIT: just looked - 3rd edition of Marion and Heald is now in Dover. The TOC and index indicate that the third edition does discuss transmission lines, waveguides, and impedance matching