Talk:Reciprocity (electromagnetism)

message: I just did a journal club on different methods used for on chip optical diodes. I must say I'm confuse about the relation between time reversal symmetry and reciprocity. Does reciprocity always imply time reversal symmetry? I think I understand the two are identical in the basic two port example? All the new work on PT symmetry and reciprocity just adds to my confusion. Any advice from an expert is appreciated.  — Preceding unsigned comment added by Eranus (talk • contribs) 08:23, 12 December 2011 (UTC)
replies: text: Reciprocity does not imply time-reversal symmetry. An electrical network which includes resistors may be reciprocal, but does not have time-reversal symmetry - no applied signal can induce the resistors to turn heat back into electrical energy. The article states this (for EM fields) in the Conditions and proof of Lorentz reciprocity section. --catslash (talk) 00:17, 13 December 2011 (UTC)
thread_title: relation between time reversal symmetry and reciprocity 

message: The proof of reciprocity is very interesting. It seems a modern proof. could you offer a old proof or give a list of references. It is very interesting to us to know who contributed to notice that reciprocity has some limitations and need to be extended.  
 
The following formula is very interesting, it seems very useful. It is better to offer a list of reference who  contributers to it.
:- \int_V \left[ \mathbf{J}_1^* \cdot \mathbf{E}_2 + \mathbf{E}_1^* \cdot \mathbf{J}_2 \right] dV = \oint_S \left[ \mathbf{E}_1^* \times \mathbf{H}_2 + \mathbf{E}_2 \times \mathbf{H}_1^* \right] \cdot \mathbf{dA}  
Imrecons (talk) 09:22, 6 June 2014 (UTC)
replies: text: This approach to reciprocity is briefly discussed in this book; although the discussion of reciprocity is very brief, mainly in an appendix, it follows from a more general discussion of Hermitian operators in chapter 2. — Steven G. Johnson (talk) 18:44, 6 June 2014 (UTC)
thread_title: Reference is required 

message: It would be very much useful to actually see how the theorem is applied in practical applicartions. One such important and recent application is to allow a new type of full duplex of receive and transmit in RF devices, such as mobile phones, WiFi and now also LiFi. Referenced here: 
http://www.svmi.com/new-full-duplex-radio-chip-transmits-and-receives-wireless-signals-at-once/ and here:
http://spectrum.ieee.org/tech-talk/telecom/wireless/new-full-duplex-radio-chip-transmits-and-receives-wireless-signals-at-once
However, this is beyond my abilities to describe and explain. Jahibadkaret (talk) 05:56, 18 April 2016 (UTC)
thread_title:  More Descriptions of Applications 

message: A section of the article starts thus:
————————————
May I ask, could this wording be simplified without loss of meaning by removing the mention of Hermitian operators and instead directly using complex-symmetric matrices? Then the text could read:
Other simpler expressions would follow.Chjoaygame (talk) 06:44, 20 April 2016 (UTC)
replies: text: \mathbf{J} = \hat{O}\mathbf{E} is not a statement about cause and effect, it is simply the statement that there is a linear equation relating current and field.  If it makes you feel better, write it as \mathbf{E} = \hat{O}^{-1}\mathbf{J} where the inverse operator \hat{O}^{-1} is essentially integration with a Green's function. — Steven G. Johnson (talk) 21:16, 17 May 2018 (UTC)
thread_title:  Hermitian matrices 

message: I  stumbled upon this article while writing an an equation sheet for OpenStax University Physics.  I presume the Reciprocity Theorem explains the equality of mutual inductance (M12=M21) as encountered in first-year physics and engineering textbooks.  Please let me know if you ever make that more explicit.  Your article is currently linked via a permalink to the word "Likewise" in my formula sheet.  Explaining reciprocity in this context would greatly enhance the utility of this article for my formula sheet and for the community at large, IMHO.--Guy vandegrift (talk) 03:45, 2 March 2018 (UTC)
thread_title:  You should tie this article to mutual inductance because  it comes up in introductory college courses