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Thread: Why the black objects absorb more light and heat from the ot

  1. #1 Why the black objects absorb more light and heat from the ot 
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    Why the black objects absorb more light and heat from the other color objects?
    What is the structure of the black color?


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    The Doctor Quantime's Avatar
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    Black isn't a colour. What you are seeing with black is nothing. Most of the energy of a photon is absorbed by the electron. This is why it is called a 'black body'. The nature of colour is described in the 'photoelectric effect' by Albert Einstein.

    Seeing as heat as well is photons, these electrons are absorbing photons and taking their energy. The energy they take is proportional to the energy level within the atom they are 'jumping' to, (often reffered to as 'Quantum Leaping').

    For instance, a photon comes along to a 'grass' atom. The 'grass' atom's electrons only absorb so much 'white light' from the sun and thus give off energy the frequency of green light:

    E = hf

    Where E is the energy of the photon
    Where h is the Planck constant (6.6260755x10^-34)
    Where f is the frequency of the photon (radiation)

    So in a 'black body' the electrons need a lot of energy from the photons and hence no energy hardly comes to the eye, so you 'see' black. In fact the only reason you can 'see' black is because other objects around it make it stand out, much like black holes.

    Here is an image of Electromagnetic radiation in terms of what I was referencing earlier:



    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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    So in a 'black body' the electrons need a lot of energy from the photons and hence no energy hardly comes to the eye, so you 'see' black. In fact the only reason you can 'see' black is because other objects around it make it stand out, much like black holes.
    But isn't the photons itself enegy?
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  5. #4  
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    Yes they are. Photons are also reffered to as 'packets of quanta'. Quantity, energy. Photos are the most principle form of energy that we know of.
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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    Quote Originally Posted by svwillmer
    Yes they are. Photons are also reffered to as 'packets of quanta'. Quantity, energy. Photos are the most principle form of energy that we know of.
    So in the black bodies, need a lot of more energy, right?
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    Quote Originally Posted by scientist91
    Quote Originally Posted by svwillmer
    Yes they are. Photons are also reffered to as 'packets of quanta'. Quantity, energy. Photos are the most principle form of energy that we know of.
    So in the black bodies, need a lot of more energy, right?
    A body that is 'black' will tend to absorb more radiation in the visible spectrum and will therefore, ceteris paribus, become hotter (absorb more energy -> heat) than a body that reflects more of that light away.

    'Need' perhaps goes too far in terms of reifying the colour black and personifying a body that is black.
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    Simple answer: black colored objects appear black colored because they absorb light instead of reflecting it.

    An object that appears to have a given color has that color because it reflects that color of light (and absorbs all other colors). Black doesn't reflect anything. White reflects everything.


    You might as well ask why tall people have long legs, or why gas guzzling cars consume so much gas. (I'm just giving you a hard time)
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    Quote Originally Posted by kojax
    Simple answer: black colored objects appear black colored because they absorb light instead of reflecting it.

    An object that appears to have a given color has that color because it reflects that color of light (and absorbs all other colors). Black doesn't reflect anything. White reflects everything.


    You might as well ask why tall people have long legs, or why gas guzzling cars consume so much gas. (I'm just giving you a hard time)
    Do they release that energy, later?
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    Do two objects of the same size,same material,but different in the colour,weight the same?

    Can't Two different objects reach the same weitgt if radiated with two different coloured lights?
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    Why Wt/At=Wt(black body)
    Why At=1?
    Stephan-Boltzmann law.
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    did you not learn about colours in school/college?
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    Allot of the questions (and even sometimes myself) that are asked on this forum are due to lack of perception. Most people will only look at something one way, and force themselves to try to understand it through those means, when really they are very inefficient and will likely never yield the desirable result.

    You need to put most your time into varying your initial perception so that you can use considerably less energy later on.
    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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    Quote Originally Posted by Cold Fusion
    Allot of the questions (and even sometimes myself) that are asked on this forum are due to lack of perception. Most people will only look at something one way, and force themselves to try to understand it through those means, when really they are very inefficient and will likely never yield the desirable result.

    You need to put most your time into varying your initial perception so that you can use considerably less energy later on.
    Please explain if you know why it is 1?
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    Quote Originally Posted by scientist91
    Why Wt/At=Wt(black body)
    Why At=1?
    Stephan-Boltzmann law.
    If you are referring to the emissivity, it is 1 because 1 means all, or 100 percent. A black body by definition absorbs all the incident light and emits light as a function of the temperature. Gray bodies only emit a portion of what a black body emits, and that portion is the emissivity.
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