Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electromagnetic waves.

  1. Nov 28, 2003 #1
    hi all,
    Can anyone tell me a easy way to create radio waves,micro waves reciver and emiter?

    I hope someone will help me.

    all for God.
  2. jcsd
  3. Nov 28, 2003 #2
    there are many ways. for example you can use a magnetron for emmiter and (surprise !!!) a antenna for recieving.
    What do you wanna do?
  4. Nov 29, 2003 #3
    I want to create it at home for use(experiment).
    anyway you were the one who told me about smart antenas. :wink:

    All For God.
  5. Nov 29, 2003 #4
    If you are unqualified in radio, as seems from nature of question, you shouldn't mess with radio emitters at home. Definitely not with magnetron.
  6. Nov 30, 2003 #5
    What on Earth is a Magnetron? Many thanks.
  7. Nov 30, 2003 #6
    It’s a vacuum tube having several cavities with a central filament to emit electrons. A high gauss magnet is placed outside the tube with the poles on opposite sides of the magnetron. The magnetic fields cause the electrons to spiral as they move toward the anodes through the cavities. The accelerating electrons emit photons. Those photons of the correct frequency will resonate in the cavity, thus producing high frequency radio waves. It was a WW2 British invention, which made radar possible and helped to win the air-war. If you have a micro wave oven, it uses a magnetron to make the microwaves
  8. Dec 2, 2003 #7
  9. Dec 28, 2003 #8
    Electromagnetic spectrum


    I have some mind boggling questions that haven't been answered in the 21 years of my existence.

    The main question is...

    If light is part of the electromagnetic spectrum, then why is it so much different than the other parts of the EM spectrum?

    When we study EM waves... we study Light independently.

    We study the refraction, diffractions, etc. of light... but there is usually no mention of refraction, diffraction, etc. of other waves.. like microwaves.

    Why is it?

    Also, why is it that a book can block EM waves in the light's spectrum... but almost any other waves in the EM spectrum can pass through it (microwaves, etc.)?

  10. Dec 28, 2003 #9
    Re: Electromagnetic spectrum

    Actually, in itself, visible light isn't different than the rest of the EM spectrum. Are eyes are such that we just perceive a narrow band of that spectrum and we refer to that as visible light. The only physical difference is wavelength and inversely, frequency.

    Sometimes the term light is used to mean electromagnetism in general. Sometimes it's used to refer to visible light only. It depends on the context in which it is used. Ex: The speed of light in a vacuum is C(299,792,458 m/s). This applies to electromagnetism in general.

    When studying EM in general, it necessarily includes visible light as well. It's not surprising that visible light is also studied independently. It's the range of EM that we were aware of first. It's the part of the spectrum that we directly perceive in a very specialized way. The field of optics is primarily concerned with the study of visible light as well as infra-red and ultra-violet light.

    Of course, other parts of the EM spectrum are studied independently as well. Radio, microwave, infrared, ultraviolet and x-ray EM are studied independently.

    Diffraction, reflection, scattering, etc applies to all parts of the electromagnetic spectrum. Quantum Electrodynamics is the study of electromagnetism, electrons and their interactions with each other.

    A web search for micro-wave diffraction, x-ray diffraction, etc, will yield many hits.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook