What is Tem: Definition and 35 Discussions

The Tém (also known as the Temba or Kotokoliare) an ethnic group of Togo, but also found in Benin and Ghana. There is reported to be about 417,000 of the Tém, with 339,000 in Togo, 60,000 in Ghana and 18,000 in Benin. They speak the Tem language.

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  1. Y

    Maxwell's equations for TEM mode

    Dear All, I'm confused after reading of some chapter in a book, in which equations related to TEM mode have been derived. I want to prove mathematically, that Electric and Magnetic fields are ortogonal to each other. Thus, I use well known Maxwell equation: $$\nabla \times \overrightarrow{E} +...
  2. I

    Wave propagation - Oblique Incidence

    Summary:: A plane wave incident upon a planar surface - determining polarization, angle of incidence etc. 𝐄̃i = 𝐲̂20𝑒−𝑗(3𝑥+4𝑧) [V. m−1 ] is incident upon the planar surface of a dielectric material, with εr = 4, occupying the halfspace z ≥ 0. a) What is the polarisation of the incident wave...
  3. T

    A I made a website to index TEM diffraction patterns

    Hi, I spent some time during my PhD with the task of indexing TEM diffraction patterns, usually made with selected area diffraction. All available software I found online was either too complicated or too expensive (or both). So I decided to make my own: https://www.odpin.com It's 100%...
  4. V

    What are some examples of circuit simulations with self-managing surges?

    I spend a lot of my time simulating circuits whose salient feature is their tendency to surge. I like all surges, but especially those which have any potential to be managed... http://is.gd/constcurr The non-manageable ones tend to blow up very suddenly... http://is.gd/kaboomopamp My favorite...
  5. A

    Why is del(E_t) zero in TEM mode of transmission lines?

    I was going through MIT opencourseware https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-013-electromagnetics-and-applications-spring-2009/readings/MIT6_013S09_chap07.pdf and I didnt understand exactly why in equation 7.1.37 and 7.1.38 in page 192 the divergence of...
  6. C

    I Why is the resolution of TEMs and SEMs not smaller?

    I was wondering if someone could offer an explanation as to why TEMs and SEMs have practical resolutions several orders of magnitude less than what is predicted by the Rayleigh Criterion. This of course comes from my own calculations of the Rayleigh Criterion assuming an electron is accelerated...
  7. yabb dabba do

    Current, B, E field directions on line in TEM mode

    Hi, Say you have a two conductor transmission line in TEM mode. The E and B field's will look something like the picture below with the E field in blue and the B field in red. The E field should point in the direction of the current, as it's what makes the charges move. The E field in the...
  8. O

    Electric field in coaxial cable

    Every physics books show that wave prograpation in coxial cable is TEM wave, like in the picture. But we know that J=σ E from ohms law, which says current in same direction with E field, which is not the case here. What do you think the reason is ?
  9. M

    Analyzing diffraction pattern with ImageJ

    Hey! I have a very unusual question. It is about using ImageJ to analyze diffraction patterns from TEM. 1. Homework Statement To calculate lattice parameter I need Miller Indices from planes I can recognize in the picture, wavelength of electrons and camera length. In our instructions for...
  10. Telemachus

    Transmission Electron Microscopy

    I'm looking for a quick and well synthetized reference to the TEM technique. I'm writing a monography, we used TEM on a sample (just sended it to the lab, I dind't do the work). I don't have any reference, and I wanted to give a kind of introduction in the monography to TEM. I don't want a whole...
  11. D

    Time to raise tem from 25 to 145 celcius

    im trying to work out time it takes to raise the temperature of cookie dough from 25 celcius to 145 celcius. E=m*spec heat *(145-25) I have E=.012*2900*(120)= 4176j, how do I work out the time it takes. thanks in advance
  12. G

    Laser TEM Modes - What Determines Output?

    What determines which TEM mode will the laser output have? Why some lasers emit in TEM00, while other in a donut mode, and other in a superposition of multiple modes. Thank you.
  13. baby_1

    What'a difference between TEM wave and plane wave?

    Hello what'a difference between tem wave and plane wave? I think in tem is the same as plane wave but it's electromagnetic amplitude decrease ,is it right?if yes how does amplitude decrease?
  14. fluidistic

    TEM mode propagation between 2 infinite conductor plates

    Homework Statement I am trying to solve a problem from Jackson's book (in chapter 8). I must describe the propagation of a TEM mode through a transmission line that consists of two infinite conductor plates that are parallel to each other and separated by a distance a. There's a dielectric...
  15. vead

    TEM TE and TM Modes for Waveguides ?

    hello ; I need some help.I reading about TEM TE and TM Modes for Waveguides. actually I need some equations for Planar wave guide and optical fiber wave guide. I did google search. I don't understand how to write equation step by step for planar wave guide I found this link...
  16. F

    TEM Analysis of Hydroxyapatite (Ceramic)

    What information do you get from TEM images and how do yo obtain it? I am analyzing hydroxyapatite (ceramic).
  17. Rapier

    Understanding TEM Calibration Patterns: NiOX vs SiGe Explained

    Ok, so we were doing TEM and at the end we were looking at calibration patterns and I'm preparing the presentation and I am writing the intro but I realized I'm not sure why the calibration pattern looks like concentric circles. I believe it is because we are scanning the beam across the sample...
  18. K

    Why do TEM modes need two conductors to propagate?

    Why do we need two conducting surfaces to allow TEM modes to propagate through a waveguide? Why can we not propagate TEM waves through a single conducting waveguide?
  19. S

    TE, TM and TEM Modes in Lasers

    Greetings everyone, I am confusing the definitions in the title of the post all the time. I have books about lasers, yet none of them explain these concepts lucidly and clearly in my opinion. For example, what is our reference plane when we are dealing with semiconductor laser diodes and...
  20. Y

    Question of reflection and transmission of TEM wave in normal incidenc

    Suppose TEM wave in +z normal to a boundary on xy plane at z=0. We know E & H are tangential to the boundary. Let ##\vec E_i=\hat x E##, be the incident wave towards the boundary therefore incident H is ##\vec H_i =\hat z\times \hat x \frac {E_i}{η}=\hat y H##. I have a few questions: 1) How...
  21. O

    E-field polarization in the direction of propagation, TEM, TE, TM

    I read that for a plane wave E, B and k are always perpendicular to each other but then in a TM mode I have electric field in the direction of propagation. This means this TM and TE modes I cannot have in free space? Can I have them in a laser? If I can have some E-field in the direction of...
  22. F

    TEM plane waves, decay and attenuation

    I've been trying to get reantiquated with electormagnetics to understand RF communications better. I have a question about TEM plane waves. The funtions which describe the plane waves in the z dirrection are: e-α cos(ωt-βz) ; in the time domain where is the rate of decay. In free...
  23. N

    Something to be clarified about EM Wave: TE, TM and TEM

    I have been reading different articles about EM wave modes, it is said that in TE waves the E_z is zero, similarly for TM H_z is zero, and TEM both E_z and H_z are zero. How about the E_x and E_y in TE wave? Someone said E_y is also zero and only E_x exists in TE...is this true? Is it...
  24. K

    Why can we see light when looking down a metallic tube? TEM modes can't exist.

    Hey everyone, I'm going over my course content for an exam this Saturday and I'm a bit confused by a realisation I've just had. In a metallic waveguide we know there are no TEM modes. But wouldn't this mean that we couldn't see through metallic waveguides as we see electromagnetic radiation...
  25. E

    What is the Truth About the Magnetic Field in TEM Mode in Transmission Lines?

    As for transmission line(which operates on TEM mode), electric field is created by the opposite polarity of surface charge on both conductors, and magnetic field is by the electric current in both conductors. These two fields are perpendicular to each other, which makes "the" TEM mode. Then...
  26. F

    Mastering TEM Grid Handling: Tips and Tricks for Successful Sample Preparation

    I'm wondering if I can make this task easier, since I've ruined a lot of grids lately. Currently, I'm trying to use tweezers, but I lack the subtlety to grip them firmly enough without bending them. We can't use vacuum on them since it would potentially contaminate our samples. I've thought...
  27. Y

    Limitations of Using E to Find B in TEM Waves

    I have questions: 1) What is the limitation of using: \vec H ( \vec r, t) =\frac 1 v \nabla \times \vec E(\vec r, t)\;\hbox { where }\; v= \frac 1 {\mu \epsilon} I know for this formula to work, the medium has to be charge free. I want to know in what other cases I cannot use E to find B. I...
  28. Y

    Question on TEM wave travel in parallel plate transmission line.

    I want to confirm that the TEM wave is actually travel inside the dielectric between the two plates of the parallel plate transmission line. So even though surface current and surface charge appeared on the surface of the conductor plates as the consequence of the boundary conditions between the...
  29. Y

    Question on TEM representation used in Griffiths book

    I am confused with this part of "Introduction to Electrodynamics" 3rd edition by Dave Griffiths. On page 367, the traveling wave is represented by: f(z,t)\;=\; A cos[k(z-vt) \;+\; \delta] 9.7 Where v is velocity and kv=\omega. This give: f(z,t)\;=\; A cos[kz \;-\;\omega t \;+\...
  30. Y

    Question on TEM mode transmission lines.

    I want to verify the theory of TEM mode tx lines how the signal travel. Please correct me if I am wrong. This mainly refer to stripline, microstrip( assume TEM) etc. 1) The signal is transmited as EM wave through the dielectric between the two lines, not actually current through the...
  31. Y

    Help in TEM wave propagation for a solenoid or magnetic dipole.

    I am trying to figure out how the TEM wave looks like and how it propagate outward. Attached is a pdf of a drawing with only the solenoid and show the winding that the current is flowing in CCW and a reference. Also I draw a loop with one resistor and show the induced current and the polarity of...
  32. K

    A Question On Electron Microscopy (TEM)

    Homework Statement Hello! The question is as follows: 1. You are provided with a 1 cm3 of biological sample from which 0.1 mm thin sections are cut. A search for virus cells at a magnification of 100,000 has been proposed. The fluorescent screen on which the image is to be projected...
  33. P

    Is color added to SEM and TEM images in post-processing?

    I saw in some papers SEM colored images. Does anybody have an idea about the software that may be used?? and how? thanks
  34. J

    When to Use TE, TM, & TEM Modes for Modeling Optical Fields

    Can anyone point me to an online resource which gives details - and applications - as to when one should model an optical field using TE and TM modes, and when it's OK to use TEM modes. Cheers. edit: should've stuck this in the normal physics forum... mods please move... More specifics...
  35. C

    Maxwell Equations and Waveguide: why only TE or TM wave and not TEM?

    I have posted this in some other physics forum, however, I have not yet gotten any definite answer. Hope some of you can help. I have been trying to understand why in a hollow metal tube, the Maxwell equation admit wave solution, and that they are always TE or TM. In all of the textbooks I...