Physical processes involved when seeing, and comparisons between with other light detection systems. Includes questions about the eye, optical nerve, brain, corrective lenses, etc.

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2answers
44 views

Why do you need at least two rays to form an image?

Why isn't enough one light beam to form an image in your retina for example?
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1answer
44 views

How we are able to see red and green colored objects simultaneously if combination of red and green produces yellow?

If red and green cones in our eyes are tiggered simultaneously then our brain makes us see yellow color. But if two objects which have red and green colors respectively are placed infront of us then ...
2
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0answers
25 views

Terminology - optical (visual) properties of a structure

I am trying to understand few terminological problems that I encounter. Without knowing keywords it is hard to perform search for literature or publications in the area. The area relates to the ...
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1answer
70 views

What happens to photons, electrons, etc [duplicate]

What happens to photons when they hit our eye? where do they end up? if they generate heat, why our eye don't get overheated? Similarly what happens to electrons when the light hits certain metals, ...
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0answers
29 views

Reference request for relativistic imaging

Being a high-school physics teacher, I always am searching for compelling and different approaches to the subject. In the case of (special) relativity a frequent curiosity arises while discussing what ...
2
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1answer
72 views

Why do we see just one octave of light? [closed]

When one takes a look at the usual chart of EM spectrum one cannot help but notice that visible spectrum is slightly below one octave of frequencies; that is, the ratio between the highest and least ...
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4answers
2k views

3D glasses giving the opposite effect to that expected

I have just finished watching the new Star Wars movie (The Force Awakens), and during the end credits, text is shown upon a background of stars. Wearing the 3D glasses, I noticed that the text appears ...
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2answers
69 views

Speed and multiple images

Why an object (or something else) create multiple images of itself when it is moving fast? An earphone spinning in circle for example.
3
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1answer
68 views

White LEDs and colour perception

I’m very interested in LED lighting and the different spread of wavelengths that are produced compared to other types (like tungsten). Given that a White LED bulb actually produces 3 different peaks ...
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2answers
680 views

How many frames can human eye see? [closed]

What's the limitation of our eyes? Can we differentiate 60fps from 120fps? Are new 144hz monitors just a marketing trick? Couldn't find any proper journals or studies about the matter.
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1answer
40 views

How Vision Works [closed]

Vision works when we receive the reflected wavelength of white light from a particular object. There is a single angle of reflection depends upon the light's incidence angle. If so, how can many ...
13
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3answers
2k views

Is it possible that a person with myopia will see a blurry picture as normal? [duplicate]

I am trying to process an image in good quality to appear blurred to a normal person and good to a person suffering from myopia as seen in this source. Is it possible that a picture that is blurry ...
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1answer
26 views

Correcting Myopia with a Diverging Lens

My textbook says that a diverging lens works by rendering the object a virtual image at the myopic eye’s far point. However, wouldn’t the eye then perceive an object farther than its far point at the ...
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2answers
38 views

Space station illuminated by the Earth

Let's say that we have a space station orbiting the Earth around the equator at a speed of 360 degrees per 24 hours, always being roughly on the line between the centers of the Earth and the sun. From ...
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0answers
18 views

Modeling total absorption using absorbance of multiple visual layers

I have a question involving light absorbance versus absorption. It applies to a stack of different photoreceptor types. I understand the difference between absorbance, which is basically equal to ...
0
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0answers
19 views

What mega pixel are human eyes? [duplicate]

I always wonder with cameras improving still what I see from eye can almost never come close to that of camera particularly in low light. So what is the mega pixel resolution of human eyes?
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0answers
68 views

Is is true that if they can see me I can see them? [closed]

You all know the joke kids do - they cover the eyes thinking that if they can't see me, I can't see them. I wonder if there is truth to it? If I can see you from somewhere (let's say a hill), then is ...
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1answer
89 views

How fast would you have to run to create a mirror image?

So I was watching The Flash and in the most recent episode he runs so fast that he is able to create a mirror image of himself so that it looks like there is more of him than there actually is. So I ...
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2answers
75 views

Humans and color at night [closed]

Why we can't see colors at night?
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1answer
70 views

Why do 3d movies have a red and blue “double image”? [closed]

My question is why do 3d movies have a red and blue"double image" that is basically just a few inches to the right and left of the real image. And how does this help us see the image as "3d". Does it ...
7
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5answers
603 views

Perception of Depths and Stereovision [closed]

I watched a video on Youtube and read a few articles which say that human beings see 3D because we have two eyes. But does that mean when I close one of my eyes, I should see 2D? It doesn't happen so. ...
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2answers
183 views

Light and vision (why we can't see without light) [closed]

I have heard that light comes from object and we are able to see the image of that object. But I can't understand why we can't see without light and how we are able to see object but not in dark. MY ...
0
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2answers
63 views

Is it possible for two strong lenses to cancel each other effects?

Is it possible for a lens system for 2 strong lenses to cancel each other, so it looks almost the same as a common glass, while at the same time making an object in between them appear big and ...
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5answers
2k views

Why can't we see infrared light?

While explaining to my nephew about the physics of light, I told him we cannot see infrared color, and he kicked back with a very simple question: why can't we see it? I could not tell him. Is the ...
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0answers
62 views

What is the minimal size of the spec of dust I can see with naked eye?

When sun directly shines thru the window - I can see small specs of dusts in the air. All specs have different sizes. Assuming direct sun luminosity is 100kLux, spec is a perfect sphere, reflection ...
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2answers
561 views

Why we can't see light emitted from TV remote while a camera can?

If we try to see light emitted from tv remote we can see this. while if we try same in camera we are able to see this. Why?
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0answers
38 views

Can a person with bad vision see a blurry picture clearly? [duplicate]

I was just thinking to myself how weird it must be to have bad vision. Then I thought, I wonder if you could print a picture that would appear clear to someone with bad vision. That seemed unlikely to ...
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4answers
5k views

Why does a moving fan seem transparent?

We all know when fan starts moving faster, we cannot see its blades. Why is this? First I assumed persistence of vision may be the reason. But that can happen with blade also right? Image of blade ...
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1answer
25 views

Computing color and brightness of a hot material

Every blackbody color calculator I've managed to find only calculates hue and saturation; they completely ignore brightness, which severely limits their usefulness if you're trying to model the actual ...
3
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1answer
178 views

An object glows red at around 1000K while a red star is around 3000K. What causes this misalignment in spectra?

According to the H-R diagram, a red star is 3000K, a yellow star is 6000K and a white star 10000K. But a hot metal appears red at 1000K, yellow at 1500K and white at 2000K.(approximately) Why is ...
3
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1answer
112 views

Mechanism for visible light frequency mixing in storm clouds

So I know that when red and blue light (or the frequencies/wavelengths we percieve as such) hit our eyes with the correct proportions, our eyes and brains interpret that as the color purple. In ...
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1answer
415 views

What is the frequency of the color black?

Our eyes don't see light; they detect vibrations in the 400-800 THz range that we call color. Since our eyes can detect the color we call black, what is its frequency?
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0answers
101 views

How do I translate from CIE xyY color space to combinations of monochromatic wavelengths

Let's say I have a chromaticity point, on the CIE xyY color space that falls within the real colors. (Like y:0.1, x:0.4 Y:1 -- magenta)[1] I also know that humans can perceive the same color, when ...
0
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1answer
110 views

What is the visible spectrum to common mobile phone cameras? [closed]

With my iPhone I can see the IR emitter on a tv remote, which could be around 940nm, but I thought cameras generally tried to filter for the human visible spectrum (i.e. sub 700nm). I'm trying an ...
0
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1answer
77 views

What would the rainbow look like if we could see the full EM spectrum? [duplicate]

Would the rainbow look different if we could see the full EM spectrum (or at least a lot more of it)? Would the width of a rainbow be bigger and would all wave lengths of light be in a rainbow?
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1answer
112 views

Estimate the amount of atoms in the smallest speck of matter you can see with the naked eye [closed]

I am currently working through a physics text book at my own pace on Newtonian mechanics. I came across this question in the the chapter 1 problems and had a bit of trouble with it. My biggest issue ...
4
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1answer
86 views

What, if anything, makes primary colours distinct?

I've recently become interested in the primary colours; red, green and blue. In my capacity as a computer programmer I'm well aware of how these colours are used practically, and of how varying ...
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0answers
30 views

Chromatic aberration in human eye [duplicate]

A lens focuses the different colours of white light at different points. Since our eye has a convex lens there should also be such an aberration but we see objects clearly with normal eye. I want to ...
6
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0answers
287 views

Why can I turn light red or blue by holding my finger up to it?

This is a difficult phenomenon to explain. Imagine you have an opaque object partially covering a very bright light source, for example, an object held up against the sky. The left hand diagram is ...
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2answers
311 views

Why do we (3 dimensional creatures) see in 2 spatial dimensions? [closed]

Why do us humans, as 3-dimensional (in terms of space) creatures, see everything in 2 dimensions? Is it because the surface of every 3-dimensional object is 2 dimensional? Or because light enters our ...
0
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1answer
140 views

Why does the sky look blue rather than violet? [duplicate]

Sky looks blue because because our eyes are sensitive to blue colour. But when viewed through a camera why don't we see violet of the sky even though we can see violet colour of other pictures taken ...
0
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3answers
353 views

Is purple in visible light?

This isn’t a duplicate. I read those pages, but those didn’t answer my questions. Please watch this. Does visible light consist of red, orange, yellow, green, cyan and blue? No purple? My definition ...
3
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1answer
103 views

How to calculate the colour a human eye sees when looking at a light spectrum?

I have to do a presentation about colourants in Chemistry class (grade 12, advanced) and want to write a program that calculates and visualizes the colours of some simple molecules. What I need is ...
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2answers
189 views

Understanding colored shadows [closed]

When I turn on white lights, these chairs cast a shadow. However, when blue LED lights are turned on the shadow turns yellow. Why is this? Is this due to interference of light or is it just an ...
5
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2answers
1k views

Can spectacles converge sunlight to an extent that it burns the eyeball?

I need to know whether wearing spectacles can cause optical harm. I saw a movie where one pair of glasses was placed on table exposed to sunlight, then the sunlight converged and focused to a point ...
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2answers
50 views

What is the maximum light difference for one to be able to see into or out of a building and equally discern objects? [closed]

In this question I am referring to the physics behind not being able to discern objects outside when in a lit room, even though you would be able to discern them if you were outside, even though when ...
3
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2answers
530 views

How we see laser light if it travels in a straight path? [duplicate]

Light travels in straight path, and our eyes detects an object's reflected light then we see the object. So if laser light is going in a straight path, how come we can see laser light?
2
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0answers
461 views

Is there such a thing as purple light? [duplicate]

This is a question as much about color perception as the physics of light. Since I have normal vision, without color blindness, I will draw on my experiences in formulating my question. I will add ...
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1answer
72 views

is it possible to extract spectrum (color in general) from an animal [closed]

if i may ask....can this be ASAP? :3 my problem: okay this is going to sound lame, but i was wondering if it is possible to extract color (specifically spectrum) from an animal. this question ...
4
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3answers
2k views

Why does the sea horizon line always seems to be at the same height as one's eyes?

I wonder why, when I look at a sea/ocean, the horizon line always seems to be at the same height as my eyes, no matter how many meters I am above the sea level. This is something I noticed when I ...