Questions related to the perception and measurement of light (primarily in the visible range), its mathematical description, the reproduction of colors by different means, color combinations, etc. Please use the tag [electromagnetic-radiation] if you want to refer to the general form of light.

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2answers
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Why aren't clouds multi-colored?

Clouds are made out of tiny droplets of water. These droplets, to my understanding, act like tiny prisms (which is why there are rainbows after rain). From my line of thinking, if we had a room with ...
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1answer
24 views

Illuminance on the vertical façade from the ground

I am trying to understand the illuminance on a vertical façade from the light reflected from the ground. And am reading this through Daylighting and Architecture book. On page 41 it makes use of two ...
55
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3answers
10k views

Why do beams of light (from torches or other directed sources) not extend to infinity?

When I'm in a dark environment, and I turn on a torch, I can see the beam of light from the torch. To the best of my understanding, the main reason why I can see the beam of light is that the light ...
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1answer
24 views

What's wrong with finding the maximum refraction angle? [closed]

I am wrong with this derivation of $1 = \mu^2$ for arbitrary $\mu$ obviously, but I can't find what's wrong. $\delta := \theta_{1} - \theta_{2} $ where $\frac{\sin \theta_{1}}{\sin \theta_{2}} = ...
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0answers
57 views

Do photons traverse through the vacuum of outer space as a helix? [duplicate]

I’m trying to understand “Electromagnetic waves”. If electromagnetic waves traverse as a helix then do photons traverse as a helix?
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0answers
11 views

Light scattering and absorption in material

I would like to get your inputs on a way for measuring light characteristics (scattering + absorption) in a specific tissue. My aim is to compare characteristics at different wavelength vis and nir. I ...
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0answers
31 views

Intersection point of two wires

When I observe two thin wires (up to 1cm, relatively) at a distance, if those two wires are intersecting (but may or may not have physical contact) the absolute point of their intersection is ...
1
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0answers
28 views

Can Medium Density Slows down the Time? - Light [closed]

fact : "Light get slow down while travel through Glass (dense medium), when escape glass (dense medium) it get speed up" Isn't above situation is an open example time get slowed down for light ...
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0answers
30 views

Is there a type of light or laser invisible to the naked eye that could reflect an image off a mirror? [closed]

im trying to reflect an image on a mirror with a light or laser that is invisible to the naked eye.
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2answers
155 views

Why aren't the hottest stars mostly invisible due to radiating mostly in ultra-violet? [duplicate]

The hottest stars have surface temperatures in the range of 40,000K. Wolfram Alpha says that such a star acting as a black body should radiate almost no energy in the visible spectrum. Why then do ...
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3answers
68 views

If energy of a wave is proportional to frequency, why are higher-powered lightbulbs brighter?

E = hf. Got it. P = dE/dt, right? Not seeing an amplitude anywhere in the formula, so shouldn't the power rating on the lightbulb only be driven by the color? Is it a problem with the way the ...
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2answers
51 views

how to see photons

I recently saw a couple of videos, in which you could visualize photons traveling through something (a bottle, for example). So my question is: how does it works? How can we see light if it doesn't ...
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1answer
65 views

Why can I see a beam of light coming in through the window sometimes, but not all the time?

Does it have to do with moisture in the air? Does it have to do with the window itself? Could the light reflect/refract off of the air? If there were no moisture or smoke or dust, just air, would I ...
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2answers
78 views

Why do electromagnetic waves diffract? [duplicate]

The expansion of electromagnetic waves due to diffraction can be easily explained with Huygens' principle (and in introductory courses this is usually how it is explained). But Huygens' principle is ...
0
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1answer
39 views

What will happen if you move a photon move in a straight line with no oscillations? [closed]

As light is a wave, it travels in an oscillating pattern: | _ _ _ _ _ _ _ _ |/_\ _ /_\___/_\ _ /_\___/_\ _ /_\___/_\ _ /_\___ | \_/ \_/ \_/ \_/ \_/ \_/ ...
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1answer
59 views

Why is there a cap on the speed at which we can attain? [duplicate]

Also, If you are traveling 1 mph under the speed of light on a train and throw a baseball in front of you at 20mph what would a viewer outside the train see?
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2answers
25 views

Explanation of absorption and reflection of particular color of light by any object relating wavelength

Why do object reflect or object particular color of light? Can anyone give an explanation of by comparing wavelengths?
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1answer
19 views

Why should the ray become parallel to base in a triangular prism at minimum deviation?

In the case of minimum deviation, the refracting angles at two surfaces are equal. Then the ray inside the prism should be parallel to the base only if it is isosceles triangular prism. But everywhere ...
3
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1answer
40 views

Can we produce energy by red-shifting light

The answer on my question Does light accelerate as it nears a black hole? leads me to think that light 'gains' the gravitational energy by shifting to a frequency with a higher energy (blue). Is this ...
0
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2answers
38 views

Color(Light) Absorption [duplicate]

As per my knowledge orange color object (say orange) absorbs other color light except orange color light. So we can see orange object as orange. If this is true then is it possible "In a ideal light ...
0
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1answer
44 views

Does light accelerate as it nears a black hole? [duplicate]

As light is affected by gravity ( gravitational lending and black holes), it would seem that gravity causes acceleration. Acceleration has two parts: direction and magnitude. It is clearly evident ...
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1answer
69 views

Can a high-watt laser's scattering light be damaging to the eyes? [closed]

Heyo, I recently purchased a S3 Arctic Class IV laser pointer. I bought the 3500mW. (In case that page expires, it's 445nm wavelength, 1.5mRad variant, NOHD is 279m, beam distance at 0.25 Lux 72km.) ...
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1answer
61 views

If a car is travelling faster than the speed of light, do the headlights still work? [closed]

If a car is travelling faster than the speed of light, do the headlights still work? If you can help because i really need to know i am going on a trip with my car tomorrow!
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3answers
70 views

If light slows down while passing through a material, does it speed back up while in a vacuum?

Light slows down while passing through, say, water. After passing through the water, does the light speed back up to the "speed of light"? If so, how and why?
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2answers
75 views

Can we look across Time? [closed]

A photon moves across space, but it does not move across time. If we look at a galaxy that is 1 billion light years away, then we see that galaxy as it appeared 1 billion years ago. Now the ...
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0answers
24 views

Frequency or Wavenlenght; which changes when light is passing from rarer to denser medium? [duplicate]

what changes; Frequency or Wavelength when light passes from a rarer to a denser medium?And Why?
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0answers
49 views

Scaling of the CIE RGB color matching functions

In the CIE color system, the RGB color matching functions look like this when plotted (I'm unsure what the unit of the Y axis is) https://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_RGB_color_space ...
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0answers
50 views

Laser shone at liquid jet

When a liquid jet of water falls in laminar flow, it hits a surface. If this contact point, between the surface and the jet, is illuminated by a laser. Rings of light can be seen forming around the ...
3
votes
2answers
36 views

How exact does the wavelength of light have to be to be absorbed by an atom? [duplicate]

I have been reading sources such as this on absorption and emission which make statements such as: The interesting thing is that each atom will only absorb photons with exactly the right energy. ...
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0answers
25 views

When is an image formed?

Every part of the page is illuminated with reflected light from your forehead, your nose, your chin, and every other part of your face. You don't see an image of your face on the page because ...
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0answers
3 views

does colour of compound affects the specific optical rotation at defined costant temperature and wavelength?

If analyte has a defined method of analysis for the Specific optical rotation. is it possible a change in specific optical rotation due to change in colour of same substance?
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4answers
79 views

Can light be warped by a magnetic field? [duplicate]

I was thinking and came up with the question "Can the path of a photon be warped by a strong magnetic field?" I tried searching online for an answer but couldn't find much scientific evidence of it ...
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1answer
46 views

Does every light ray have a normal?

I am currently learning about light rays and how we see things and I have recently learnt about the normal, an imaginary line. I was wondering if every light ray has a normal? Thanks.
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1answer
24 views

What happens to light when an optical cavity path length doubles instantaneously?

Let's say we have light contained in a cavity (of initial length $L$) and then instantaneously remove the second mirror, thus removing the barrier between the first and a third mirror which is some ...
0
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1answer
44 views

Light waves and water waves

I have an idea and i would like to have more information: If I drop a stone in the water some rings or waves will appear. Those rings are made of water and are behaving that particular way because of ...
0
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2answers
73 views

Are the colors of the rainbow absolute or arbitrarily assigned? [closed]

I was watching a multi-colored loading icon, and it piqued my interest. Red, orange, yellow, green, blue, indigo, violet. (Is indigo a real color? I don't know, but that's what I was told growing ...
3
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2answers
51 views

Is it possible to save the light?

I am just thinking why can't we save the light (not a bulb). Lights normally get reflect by mirror, when source is off reflection is gone or absorbed or discharged by other object in room. Can't we ...
0
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1answer
44 views

Light's speed constancy

Trying to understand the special relativity I faced a problem,and have a question, well, with the speed of light being constant in every frame, the operation s=d/t (s for the speed of light d: ...
0
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1answer
43 views

Why can I see through a window but not a wall? [duplicate]

What is the difference between a window and a wall that makes a wall opaque but a window transparent, in terms of the molecules that make them up?
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0answers
26 views

Light pollution and visibility of Milky way [closed]

Say, 1000 years ago, when there was (almost) no light pollution or air pollution, would the milky-way galaxy have been visible at night, anywhere on Earth?
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4answers
28 views

Light field 5D Plenoptic Function

Wikipedia says "Since rays in space can be parameterized by three coordinates, x, y, and z and two angles $\theta$ and $\phi$, as shown at left, it is a five-dimensional function" I'm not ...
1
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1answer
48 views

I would like to know if violet bends the least or red [closed]

I had read that violet bends the least. But most of the webpages state that red bends the least. I would like to know why it is so.
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0answers
31 views

Blackhole and light [duplicate]

I was talking with my friend about blackholes and I asked him "Why blackhole 'sucks' the photons?" He had no deeper understanding so he answered that "I dont know, may the light is affected, because ...
1
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2answers
87 views

Can light projection on a wall travel faster than the speed of light? [duplicate]

If I project a flashlight beam on a wall and turn the source, the projection (as seen on the wall) is seen moving along the direction of the turn with some speed. If I have projected it on a gigantic ...
2
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1answer
43 views

Amplitude at successive wavefronts?

Consider spherical waves emanating from a point source initially the amplitude is A, as wave travels forming wavefronts will the amplitude of each point in all the secondary wavelets be the same and ...
0
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1answer
31 views

physics of color in glints

Below, I show zooms on the glints on 3 materials: (clean) metal blade, stainless sink, artificial leather (but same effect shows on human skin). Only the sink was under artificial light. What I'm ...
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0answers
27 views

Is it possible to split a photon? [duplicate]

I read that if two photons collide than theoretically it would make light convert to matter. If you split a photon into two, will it convert matter into light? I'm a huge amateur so excuse me if this ...
1
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0answers
68 views

Light at the Speed of Light [duplicate]

Since light particles travel at the speed of light, we know it's possible for something to travel at that speed. However, since all things are relative, and if time does stop at the speed of light, ...
1
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2answers
105 views

Does light have mass? [closed]

Does light have mass? If yes, will it exert force? If no, then how are light particles are travelling at light speed? If light doesn't have mass how is it attracted by gravitational force (black ...
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4answers
96 views

Where does the energy lost due to light emission come from?

If an object lose energy when it emits light, does that energy come from the mass of the object? Examples: Does a flashlight lose mass when it's turned on? Does a regular object (like a pencil or a ...