0
\$\begingroup\$

Here is the following video that i saw (really great video):

https://www.youtube.com/watch?v=ZaXm6wau-jc

Nevertheless, I do not understand why a close conductor (first part of the video) can not propagate a electromagnetic field when we applied on it a sinuisodal signal. Actually, I know that according to the ampere's law an alternating current in a wire induce a fluctuating magnetic field around the wire and vice versa. Finally, according to the Maxwell's equations, if we have a fluctuating magnetic field, we have an electric field, and if we have an electric field we have a magnetic field and so on, so why it doesn't propagate ???

Thank you very much !

\$\endgroup\$
4
  • 1
    \$\begingroup\$ It can propagate an EM Field providing the frequency is high enough. In future post pictures and not links to videos. It might also be a great idea to review answers to your previously asked questions and accept answers that have worked the best for you. \$\endgroup\$
    – Andy aka
    Nov 9, 2019 at 15:36
  • \$\begingroup\$ Thank you for your advices. \$\endgroup\$
    – Jess
    Nov 9, 2019 at 15:51
  • 1
    \$\begingroup\$ "... a close conductor (first part of the video) can not propagate a electromagnetic field when we applied on it a sinuisodal signal." Shh! Don't tell anyone, or all of the portable AM radios in the world will stop working! \$\endgroup\$
    – Dave Tweed
    Nov 9, 2019 at 16:14
  • 1
    \$\begingroup\$ In other words, you can't believe everything you see on the Web, regardless of how good the cute animations are. \$\endgroup\$
    – Dave Tweed
    Nov 9, 2019 at 16:15

1 Answer 1

3
\$\begingroup\$

A closed conductor as shown in the video does propagate an EM wave, just very inefficiently if the loop is small. It's not until the loop gets to be an appreciable fraction of the wavelength that the loop becomes efficient. A loop makes an excellent antenna when it's big enough.

I'm afraid the author of the video was (at best) trying to simplify to the point where he was confusing the watcher, or (at worst) didn't know what he was talking about.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.