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Thread: Light intensity

  1. #1 Light intensity 
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    Is light intensity measured by the quantity or quality of the photons/wave?

    If you had a light source pass you at .8c (arbitrary) compared to .2c, would the light be dimmer? If you have a water source on the end of a car moving at 5mph, the amount of water per square foot will be larger than it would be while moving at 50mph; does light work the same way?


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    It depends on both - the number of photons incident on unit area per second and the energy carried by each photon.

    If a source of light was receding from an observer, its observed intensity would reduce for several reasons, one being that the frequency of the light would be less due to the Doppler effect (less energy per photon). There are other effects that would reduce the intensity such as that the number of photons arriving at the observer per second would be smaller and the solid angle in which they are emiitted would appear to change.


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    When the Doppler effect occurs, does the light actually elongate? If you have a piece of sting and push it together, the waves become higher at the expense of the string becoming shorter. When you shorten light's wavelength are you bringing either end (the source and the farthest reached area) together or are you essentially adding new string? In which case....is it possible that frequency itself does not equal more energy, but the resultant 'added string'?

    In experiments where we fire a single photon at a time, how is this done and how do we know that one photon is being emitted rather than (one possibility) a tightly bound cluster of them?
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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    When the Doppler effect occurs, does the light actually elongate?

    If the speed of light is constant and universal, a drop in frequency implies an increase in wavelength (the red shift). Also, bearing in mind that traditional spectroscopic instruments, such as a diffraction grating, measure wavelength rather than frequency, these would also imply that the "red shift" arises from an increase in wavelength.

    is it possible that frequency itself does not equal more energy, but the resultant 'added string'?

    The contour of a wave as usually depicted is simply a diagram - a graph of the electric or magnetic field strength against time or position. There isn't anything joining together these points as there would be in a piece of string.
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  6. #5  
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    So then what we call a wave in electromagnetic radiation is merely the best representation that we could think of rather than any sort of physical model?
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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    So then what we call a wave in electromagnetic radiation is merely the best representation that we could think of rather than any sort of physical model?

    Yes, it's a graph showing how the the electric or magnetic field varies either against time or position. A similar graph could be used to represent the displacement in a sound wave but sound waves are actually longitudinal, not transverse.
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  8. #7  
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    Do we have any idea what electromagnetic radiation looks like on the atomic level?

    My perspective of light is becoming clearer

    Another question: What entity is that of EMR's magnetic plane parallel to? Why? Do we known which plane is magnetic and which is electric?

    Pushing the posts original intention a little further (but is still light, right?): Apparently the frequency of emitted light is proportional to an antenna's AC frequency......and if electromagnetic radiation is produced whenever electrons accelerate, then we can say that the acceleration of the electrons back and forth cause the EMR. If this is so, and only acceleration is needed, then what would happen if you created a loop that infinity accelerates electrons? This could be achieved if upon reaching the original electrons maximum velocity, a second loop could instantly seamlessly continue the constant acceleration, and repeat. This would give you a 0Hz wave of EMR. Maybe it is nothing to think about, but it seems to me that you could possibly accomplish something new if this were to be flawlessly executed.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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    Do we have any idea what electromagnetic radiation looks like on the atomic level?

    I think that this question borders on the philosophical. We don't know what an electric or magnetic field "looks like" at any level - they can't be seen. The way in which the strength of these fields varies can be depicted graphically but this isn't the same as saying that the fields themselves "look like" the graph. Also, we can't visualize a photon, but it is possible to list the properties that it seems to have.

    What entity is that of EMR's magnetic plane parallel to?

    The magnetic field is perpendicular to the electric field. Light from an incandescent source would be described as randomly polarized or unpolarized - it's electric field could be in any direction at right angles to the direction of propagation. The polarization of a radio wave would be related to the direction in which the antenna is pointing. In general, it is the electric field that is most significant as it is the strength of the electric field which determines how the electromagnetic wave interacts with matter.
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  10. #9  
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    I asked this because in the Faraday Effect there seems to be very specific original plane that is then differed to a different angle perpendicular to the projection surface.
    If you rotate their source of light, will the light's plane rotate? Does the plane always come out the same? Maybe I am confusing the matter.....
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
    Reply With Quote  
     

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