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Basic questions of electromagnetic radiation

  1. Mar 10, 2012 #1
    1. How do we observe what goes through in a slit in the double slit experiment? If this is accomplished with EM that goes across the slit, then why does the electron not completely change its direction before it hits the wall. It still always hit the wall where you expect it to, even though the photon collides with the electron that goes through the slit.
    2. Can you reproduce this double split experiment with shooting through photons and neutrinos instead of electrons?
    3. Say I use an extremely powerful optical microscope to zoom into matter. After what scale will I not see colors anymore? Will this be a continual process (i.e., the color fades more and more almost continuously) or does the colors simply vanish at some critical point?
    4. Lets say there were a machine that could produce EM at different wavelengths and I dial it more and more into the shorter wavelangths from the visible light onwards (in a dark room). After a certain wavelength has passed (700nm), will it suddenly go dark or will I still see some violet until is slowly vanishes? (I assume the answer to this answer the question on the infrared side as well.)
    5. Why do we use microwaves to heat food and not infrared?
    6. Why do microwaves cause cancer and infrared does not? (should have asked this in the bio section probably).
  2. jcsd
  3. Mar 12, 2012 #2
    any nontrivial subset of answers is appreciated.
  4. Mar 12, 2012 #3


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    Staff: Mentor

    First, we cannot ever say with certainty where the electron will end up. We can only say that it has a certain chance of being detected in a certain location. When we observe the electron before it goes through the slit we don't see the wave-like properties of the electron and only see the particle-like properties.

    Absolutely. You can perform the double slit experiment at home using a laser pointer. If you are interested just do a google search and you should find plenty of sites explaining how to set it up. Doing this with neutrino's isn't feasible as they interact with normal matter so little. But, if we could shoot enough neutrinos through so that we could see a pattern build up it would be the same as the electrons and photons produce. IE they would interfere and produce an interference pattern.

    Neither. When you zoom into with a microscope, you must illuminate your object with more light as you zoom in. Near the maximum limit most objects are mostly transparent, with the edges standing out since they absorb more light. Whatever color you are illuminating the object with is what you will see as the background light. If you didn't provide more illumination as you zoomed in, you would spread the available light out too much for anything to be visible to the naked eye.

    The sensitivity of the eye falls off as the wavelength shortens. In the violet range of the spectrum the sensitivity of the eye only at about 50% or less. As you decrease the wavelength, sensitivity falls even further until it eventaully gets to effectively 0%. Same on the infrared side.

    Microwaves penetrate food much more readily and I believe they are easier to generate. Infrared generally requires a hot filament or something to produce the radiation. Microwaves do not require this. (Though they have their own dangers, so don't ever start taking apart a microwave oven unless you are trained to) They also don't heat up the entire oven, just the food itself.

    I don't think they do. Microwaves are not ionizing radiation and their only way of damaging tissue is through heating it to high temperatures.
  5. Mar 12, 2012 #4
    thx for taking the time to asnwer all of the questions
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