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Color of mirror?

  1. Apr 21, 2005 #1
    the mirror only reflects light and produce image of other objects.
    so what's the color of a mirror actually?
  2. jcsd
  3. Apr 21, 2005 #2


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    I think that technically it would have to be considered white. The colour of an object is determined by what wavelengths it doesn't absorb. A true mirror absorbs none, and white light is composed of all visible frequencies, so....
  4. Apr 21, 2005 #3
    Mirro mirror on the wall Who is the fairest of them all ?

    There is no such thing as a perfect mirror . This means it reflects most but not all light . The light which is NOT reflected is missing in the reflection.
    Therefore if the incident light is white -- then it is not white upon reflection.
    A silvered mirror is almost perfect -- but a polished copper mirror is not
    the surface absorbes some colors ( wavelengths of light ) and therefore causes a colored reflection
    . Your Ray .
  5. Apr 21, 2005 #4
    The way I would see it (pun intended) color is how we define what we see. Therefore the color is whatever the reflection is. To give the mirror a color is more of a philisophical question. Although you could well say the glass is colourless (transparent) and the material behind silver(y).

    You could extend this to say what is the color of a piece of paper when in pitch black visibility, that would normally be white by day. Techinically the paper would be now black.
  6. Apr 21, 2005 #5


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    It's more than technically, it is how it is taught in colour theory.

    The perceived colour of an object is determined by the properties of the light cast upon it.
    The perceived colour of an object is influenced by the properties of the object.

    Think about it. The range of colours that an object could have is rigidly bound by the range of light that illuminates it. FIRST.

    Only then, can the properties of the object further determine - within that narrow range - a smaller subset of colours that the object will exhibit.

    Blue light limits an object's possible colours to a blue range. A red ball will have to appear purple - or black.

    P.S. "perceived colour" is redundant. Colour is - by definition - about perception. Objects do not have colour, they have ranges of frequency that they absorb or transmit. The red ball under the blue light absorbed all freqs of light that impinged on it, and transmited none. But this does not make the ball red.
    Last edited: Apr 21, 2005
  7. Apr 21, 2005 #6

    Claude Bile

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    The colour of a mirror (or any object) is defined by it's reflection spectrum when illuminated by a white source (I personally think a green ball in the dark is still a green ball).

    The reflection spectra of mirrors is actually a very important characteristic in optics, particularly laser optics, so the colour of a mirror is not all that complex a question.

    For example, most camera lenses have antireflection coatings to reduce Fresnal reflections. Since these coatings are optimised for the yellow/green part of the spectrum, the lenses (which can be regarded as mirrors - not all mirrors are 100% reflecting) have a purplish tinge because it reflects small parts of the blue and red spectrum, but not the green. The mirror is thus regarded as being 'purple' though you would never find a physicist officially regard it as such, but the purple colour of the mirror is quite obvious.

  8. Apr 21, 2005 #7
    To All
    So a question remains does an object have a color ??
    The answer is that it does !!!!!! and this is dependant upon it's temperature for most at room temerature that color is somewhere in the infra red .
  9. Apr 22, 2005 #8
    Is infra red a colour???

    What colour are radio waves, gamma rays, etc.

    I always thought of colour as a human perception, not as what EM waves are being emitted.
  10. Apr 22, 2005 #9


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    Depends on who you ask. Animals can see well outside the human range of colours. Dogs see into IR, bees see into UV.

    I would argue that they see them as colours.
  11. Apr 22, 2005 #10
    Sorry Delta --- I use the term color to represent frequency or wavelenth it's just shorter to type . But as someone else said animals see out of our range, and 'see' in a general sense does mean to 'sense' so we 'see' infra red through feeling , and ultra violet through burning . As to Human perception God only knows what that means .
    Yours Ray.
  12. Apr 22, 2005 #11
    Your saying that Dogs can see Prime colors that we can't? Hmn, do you think that there would be any way in the future to make humans see more colors then? :rolleyes: that'd be awsome
  13. Apr 22, 2005 #12
    Actually it is thought that dogs can only see black and white ( i.e greys )
    but in electonic terms your question is simple it is just a matter of frequency change
    . (in a theoretical sense ) We do this every day with satellie photos giving false color pictures of Radar images , infra red images etc.
    Goto JPL and look at their image archives . They are almost never in true color .
    Yours Ray .
  14. Apr 22, 2005 #13


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    A prism is the best type of mirror, using internal reflection. Color changes from where you look at it.
  15. Apr 23, 2005 #14


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    Well, the primary colours are dependent on what type of receptors the eye has. Humans have red green and blue receptors, thus those are our primary colours.

    I don't know what type of receptors dogs have, but I'm sure a quick Google check will clarify. However, I doubt that they would have special IR receptors. This means they will merely see IR as a deeper red.
  16. Apr 23, 2005 #15


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  17. Apr 23, 2005 #16
    What anybody 'sees' including dogs we have not a clue -- we can tell what they react to -- dogs do not react to visual color differences --bees do react to ultra violet.
    When you say 'see' you mean some sort of internal visualisation ( which we cannot share anyway ) so you could ask does a bee 'see' ultra violet -- like you could ask does a pigeon 'see' magnetic fields. Here the question is one of conciousness and that is still a compete mystery.

  18. Apr 25, 2005 #17


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    Ah, I would disgaree.

    A bee literally sees UV. It is received by its optical receptors and processed the same. UV is just one other 'colour' in its field of view. As to exactly what the bee sees that colour as, I dunno.

    OTOH, a pigeon does not have optical receptors that pick up magnetic fields. It is a distinct mechanism. Offhand I don't know what mechanism it is, but I would guess it is similar to our sense of balance (itty bitty grains float around in a vessel in our ear, and where they fall, they stimulate hairs. That is perceived by us as 'down'.)
  19. Apr 25, 2005 #18
    Looks like we're creeping into one of the problems that always happens between science and the english language. That is defining exactly what is mean't.

    The question has now turned into what is colour?, and as shown above, the word colour is now being written in between quotation marks.

    Although many creatures react to different parts of the EM spectrum, I would define colour as what our human eye reacts to, which is about 400-800nm.
  20. Apr 26, 2005 #19


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    I believe everyone would, and the rest are kinds of light.
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