What I mean is, suppose white light falls on a red object and is reflected, so when we see the reflected light reaches our eyes we see it as red (probably because its wavelength corresponds to red). But let's say that this reflected light falls on a purple object and then reaches our eye. What color would we perceive of the purple object? If the answer is purple, then where did the extra energy come from? ( as purple light has more energy than red)
123080
When white light falls on an object the body absorbs all colors of light and reflects some colors of light which we see the object to be.For eg.A red ball reflects red color and absorbs the rest colors.So,if I throw green light on a red ball the ball will absorb that green light.Now,will the part on which the light falls must appear black as it absorbs all the light and reflects no light.But this does not happen in reality(I have experimented using laser light).Why?
102913
In designing websites and applications, I have noticed that when mixing colors with white, certain colors make white look more "greenish" or "purple-ish". This happens to a much greater degree when using tints of white.  As a designer, how can we understand how white is influenced by the colours it is contrasted with?
118111
I was thinking about elementary physics today and realised: We learned and proved that sunlight is white. But i don't understand why when you look at a picture of a satellite orbiting the sun , it(the sun) seems yellow-orrange. How could this be? It is like there is a red light bulb in the room but what you see is green.
120247
I have a set of concave/convex mirrors/lenses, and I have drawn out all of the ray tracing diagrams for each possible combination and type of image each optical element can produce. When I look at the ray tracing diagrams then reproduce the situation in the real world with myself as the &quot;object&quot;, all the scenarios make sense to me except one: when I as the object stand beyond the focal point of a concave mirror.  The image ends up as &quot;real&quot; and appears to be in front of the mirror. Now I understand that in the situation above, I as the object would stand at 6m and this would result in the image appearing at 12m. So if I placed a wall or screen at the 12m mark, the image would form on that surface (just like a movie theater screen).... at least I think I interpreted that correctly. But I still see myself when I look in the mirror?! If the image is supposed to form and come into focus behind me, what in the world am I seeing when looking at the surface of the mirror? I still see myself, just inverted. The surface of the concave mirror still has a reflection on it. It doesn't look quite like a normal flat mirror, in that the image doesn't really look like it's &quot;inside&quot; the mirror, more like it's right on the surface of it. It's really frustrating because every other possible arrangement of optical elements makes total sense to me, except this one. Any suggestions on how to think about it? Thank you for your time!
94074
I know that for an object to be transparent, visible light must go through it undisturbed.  In other words, if the light energy is sufficiently high to excite one of the electrons in the material, then it will be absorbed, and thus, the object will not be transparent.  On the other hand, if the energy of the light is not sufficient to excite one of the electrons in the material, then it will pass through the material without being absorbed, and thus, the object will appear transparent.  My question is: For a non-transparent object like a brick, when the light is absorbed by an electron, it will eventually be re-emitted. When the light is re-emitted won't the object appear transparent since the light will have essentially gone through the object?
19156
When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity take all values on $[-c,c]$ or does it just jump from $c$ to $-c$ when it hits the mirror?  Or, is the phenomenon of a mirror better explained using a wave analogy? If so, what is this explanation?
112305
On this diagram, why is the  shaped as it is?  If we are able to see lights due to low atmospheric opacity, why can't we see radio waves, when the atmospheric opacity is so low for these kinds of waves?  What does the author mean by "observable"?
29658
I have looked online to no avail.  There is two competing answers and I am curious to know which one is right.  Someone asked me this question.  If you are traveling at the speed of light can you see your reflection in a mirror in front of you?  My answer to the question is no, I would figure that in order for that to happen the light reflecting off you that would appear in the mirror must travel faster than the speed of light to actually reach the mirror (which we all know is impossible).  He says the answer is yes, that it is all relative to the current frame of reference.   Can anyone validate the correct answer with possible references?
48158
I want to create an effect on a character where their skin and clothing are effected by two different light sources. The clothing should only reflect a bright bounce light, but have the skin should not be affected by this light source.    In the example image I have two objects a cube, a sphere and three emission  lights . I want the two white lights to hit both objects, and I need the purple light to hit and reflect off of the sphere, but ignore the cube entirely (no reflections).  Someone suggested to composite the layers together, it works... but this is very impractical and cumbersome because it forces the background to be transparent and it will be a pain to try and layer together a more complex scene, especially if its animated which is what I want this effect for.  I know you can have objects ignore shadows and all kinds of other things so im hoping someone knows how to get an object to ignore light with a few settings.
93410
Energy of light is proportional to its frequency.So if light loses energy on reflecting off a surface then why doesn't it change its colour?
115726
I'm reading some texts that seam to assume knowledge of light that I'm not too familiar with. How does wavelength of light relate to the minimum distance span that can be observed (i.e. you cannot make a lens big enough to resolve individual atoms), and is this a light phenomena or an intrinsic wave phenomena?
113857
Why can't you see a reflected image on a piece of paper? Say you put a pen in front of the paper, even when light rays are coming from other sources, hitting the pen, reflecting back, and hitting the paper, there is no reflection.   What's wrong with the following "ray diagram" and why such even don't happen and the image of the pen don't form on the paper (right side is a paper)?      When then can you see the image of a torch when you shine it on the paper?   When you put a convex lens in front of the pen, why you can now see the image of the pen on the paper?
40462
Theoretically, if I shined a laser at a mirror at an angle of 0 degrees so that the light was perfectly reflected back to the light source, then I should not be able to see the light because it is not reflected to my eyes.  | |  me | |============ laser | | |   However this is evidently not the case, as I am able to see the laser point on the mirror. Why is this the case? My initial assumption is that it is due to diffuse reflection on the imperfect mirror's surface, but I am not sure.
93302
I was going through the absorption and reflection phenomenon of light and this question struck my mind as I was walking through the light filters. Why does orange filter not appear bluish if it transmitts orange light and reflects all other lights except orange?
73517
My understanding of colour is that atoms in a particular object will absorb certain wavelengths of electromagnetic radiation, and the scattered wavelengths give the object its colour. The absorbed wavelengths contribute to lattice vibrations, increasing the kinetic energy and raising the objects temperature. Is this correct?  What is the sequence of events when a solution of particular atoms is sprayed through a Bunsen burner? I don't understand this. In this case is the colour seen a result of electrons moving up and then back down energy levels?
67533
I know that the light is reflected from a object to my eyes, but I don't understand exactly how. The photons appear from the light source and disappear in my eye! Can someone explain the phenomenon of where the photons go and do to allow us to see?
50359
This is probably an obvious question, but I don't see it answered anywhere.  Imagine we have an object in the Universe that is traveling, relative to the Milkyway at about .99999999999999999999999999c and I realize that's not possible, but imagine.  Speed is relative, so to the object, the Milkyway is flying past it and to us, the object is flying past us.  That's all good and relative.  But the photons that our superfast object encounters are gonzo blue-shifted, and relativity says that's OK too.   But lets say the object is traveling so fast, the photons it encounters are energetic enough to spontaneously undergo pair production.  That seems difficult to explain.  A relatively low energy visible light photon to our perception won't split into an Electron and a Positron, but a very energetic photon can, but it's the same photon just observed by 2 different reference frames?    I understand that observers won't agree on when things happen or on energy but the two observers should agree on events that take place and pair production for one but not the other seems impossible.     Is there a simple layman's way that this can be explained?