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Homework HeLP: General Science

  1. Mar 26, 2004 #1
    Hi everybody, I'm new to the board and I need some help with these questions. Thanks.

    1. Explain why standing next to a warm thermal source is a good way to avoid mosquito bites.

    2. Explain why decreases in the zone layer led Canadian scientists to develop a system for measuring the intensity of UV radiation at ground level. The UV index that accompanies most weather forecasts is the outcome of this system.
     
  2. jcsd
  3. Mar 26, 2004 #2
    I do not know the answers to these, but making a guess...
    1. mosquito's are generally found in warmer climates and so perhaps they are simply attracted to the heat source rather than you body
    2. Perhaps this led them to realise that the O-zone layer reacts with UV soaking a certain proportion of it up and so now they can use o-zone and measure the reaction to view the level of UV
     
  4. Mar 26, 2004 #3
    I can field the first one.

    Mosquitos track their victims by heat and by shadows. They typically choose the hottest place to bite because blood is hotter than the surrounding tissue. The hotter the area, the more blood there is, and the happier the mosquitos are.

    For the second, I'm really not even sure what's being asked...

    cookiemonster
     
  5. Mar 27, 2004 #4
    But why is standing next to a warm thermal source a good way to avoid their bites?
     
  6. Mar 27, 2004 #5
    I got some more questions....

    1. Cardiologists who have access to cardiac imaging technology claim that one of the system's greatest strengths is that they can use a non-surgical technique to get in and out of the heart as quickly as possible. WHy are these characteristics so important?

    2. Why are fetuses and infants much more readily harmed by ionizing radiation than adults?

    3. WHy are x-rays not recommended for pregnant women?

    4. Although ionizing radiation is hazardous, why is it misleading to say that all types of radiation are bad? Support your answer with examples.
     
  7. Mar 27, 2004 #6

    ShawnD

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    Science Advisor

    It's obviously better if they don't need to cut you up. Surgery can always go wrong but imaging devices usually don't damage one's body in any serious way.

    Ionizing radiation sometimes causes cells to mutate. Infants and children grow very fast, so 1 mutated cell turns into thousands of mutated cells in a very short time. Adults don't grow (or regenerate) as fast as children do, so if some cells mutate, it's only a few cells in a certain area that are mutated.

    Same reason as above. Fetuses grow very fast, so any mutation by ionization can lead to serious problems.

    Ionization is mostly done by high energy (high frequency) waves such as gamma rays; you may want to google "Max Planck" and see why. The lower the energy of the wave, the less dangerous the wave is. Gamma rays are very dangerous, ultraviolet rays are not as dangerous, visible light probably isn't dangerous at all, infrared and heat waves are not dangerous, radio waves are not dangerous.
    Only high energy waves are dangerous.
     
  8. Mar 27, 2004 #7
    What types of electromagnetic radiation are used to obtain images of Earth from space?
     
  9. Mar 28, 2004 #8
    To answer your first question, it is good to have a heat source next to you in order to avoid mosquito bites because the mosquitos are more attracted to the heat source than they are attracted to you. They see the heat from the heat source and think that that's where the blood is, so they go and bite that instead of you.

    For your latest question, many types of electromagnetic radiation are used to take images of the earth. "Electromagnetic radiation" is another way of saying "light." That being said, we are not so much "using" electromagnetic radiation to take pictures as collecting it. Most of the radiation comes from the sun and just bounces right off or is emitted from the earth itself. We just use the radiation that's already there.

    Additionally, EM radiation is really all the same "type." Our classifications like x-ray and gamma ray and radio wave and microwave are all arbitrary and mostly made by our uses for those particular wavelengths.

    cookiemonster
     
  10. Mar 28, 2004 #9

    turin

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    Homework Helper

    It's a decoy.




    ?




    They have to break your ribs to perform heart surgery, last time I checked. I think not having to get in there like that would be a huge inscentive for me. The next most obvious point is that it's your heart. I mean, how long can you live without it, or even with it being severely tampered with?




    ?




    If you get an answer for 2., then note that x-rays are a form of ionizing radiation.




    Ultimately, this planet is alive by means of what power source? Hint: it is not on this planet. How does the energy get here?
     
  11. Mar 28, 2004 #10
    You sure have a lot of questions, PhYsics_Girl011!
     
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