# How does light go into the eye?

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#1
I'm really confused because we learnt about the rule of the angle of incidence=angle of reflection but how do we see all the things around us if light travels in straight lines? I know this is an extremely dumb question but I cant understand it. I attached a paint drawing to help u understand why I'm confused don't judge please
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2 years ago
#2
(Original post by idrc)
I'm really confused because we learnt about the rule of the angle of incidence=angle of reflection but how do we see all the things around us if light travels in straight lines? I know this is an extremely dumb question but I cant understand it. I attached a paint drawing to help u understand why I'm confused don't judge please
Rather than thinking about it as one straight line, think about it as loads of them, billions and trillions of them. Trillions from the lightbulb bouncing all over the room. Trillions bouncing onto and back from the surface of the desk. Since there's so many of them, some of them must get into the pupil.
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#3
(Original post by Frizzaayy)
Rather than thinking about it as one straight line, think about it as loads of them, billions and trillions of them. Trillions from the lightbulb bouncing all over the room. Trillions bouncing onto and back from the surface of the desk. Since there's so many of them, some of them must get into the pupil.
I know what you mean but wouldn't the line of incidence have to come from that area (the orange line) and if so how would it get there?
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2 years ago
#4
(Original post by idrc)
I'm really confused because we learnt about the rule of the angle of incidence=angle of reflection but how do we see all the things around us if light travels in straight lines? I know this is an extremely dumb question but I cant understand it. I attached a paint drawing to help u understand why I'm confused don't judge please
You have oversimplied you diagram...its more like this
and the same for every point on the object surface

light from the sun is multidirectional
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#5
(Original post by jsmith6131)
You have oversimplied you diagram...its more like this
yeah that's true but where would the light on the orange lines come from?
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2 years ago
#6
(Original post by idrc)
yeah that's true but where would the light on the orange lines come from?
light from the sun is multi-directional

lasers are like the only true unidirectional light source
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2 years ago
#7
(Original post by idrc)
I'm really confused because we learnt about the rule of the angle of incidence=angle of reflection but how do we see all the things around us if light travels in straight lines? I know this is an extremely dumb question but I cant understand it. I attached a paint drawing to help u understand why I'm confused don't judge please
it is not at all a silly question. we take light for granted in our lives without thinking much about what it is or how it works. so if you are looking at a wasp on your windowsill there must be "wasp photons" coming into your eyes. but as you have noticed, those photons were not specifically "wasp photons" before they bounced off the wasp. they probably started in the Sun then traveled millions of miles to our planet, through the dust of the atmosphere, hitting many different objects before bouncing off part of the wasp and entering your optics.
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2 years ago
#8
(Original post by idrc)
I know what you mean but wouldn't the line of incidence have to come from that area (the orange line) and if so how would it get there?
Okay so I'm going to assume this is a room as there is a lightbulb. In order to see that desk that clearly then than means light ito travel from the lightbulb, bounce off of the wall and onto the desk that way and then into the pupil. In the instance that there are no walls, the light wouldn't bounce off of the wall and so the desk wouldn't be well illuminated and would be in shadow. Does that make sense?
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2 years ago
#9
Light bounces off the walls travelling in numerous directions some will enter perfectly through the center of the eye whilst some will enter from an angle, due to the eyes curvature the light rays are refracted, correcting the light rays path to hit the optimal point at the back of the eye.

I have over simplified whats going on, i hope it makes sense still.
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2 years ago
#10
I think the light catches the district line from Victoria station and then goes from their to your eye. All dependent on Traffic of course. You know how London gets at Rush hour.
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#11
(Original post by tomnelson_)
Light bounces off the walls travelling in numerous directions some will enter perfectly through the center of the eye whilst some will enter from an angle, due to the eyes curvature the light rays are refracted, correcting the light rays path to hit the optimal point at the back of the eye.

I have over simplified whats going on, i hope it makes sense still.
(Original post by Frizzaayy)
Okay so I'm going to assume this is a room as there is a lightbulb. In order to see that desk that clearly then than means light ito travel from the lightbulb, bounce off of the wall and onto the desk that way and then into the pupil. In the instance that there are no walls, the light wouldn't bounce off of the wall and so the desk wouldn't be well illuminated and would be in shadow. Does that make sense?
(Original post by the bear)
it is not at all a silly question. we take light for granted in our lives without thinking much about what it is or how it works. so if you are looking at a wasp on your windowsill there must be "wasp photons" coming into your eyes. but as you have noticed, those photons were not specifically "wasp photons" before they bounced off the wasp. they probably started in the Sun then traveled millions of miles to our planet, through the dust of the atmosphere, hitting many different objects before bouncing off part of the wasp and entering your optics.
I think I understand it but is this picture correct?
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#12
it didn't let me attach the image so is the light orange line correct?
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2 years ago
#13
(Original post by idrc)
it didn't let me attach the image so is the light orange line correct?
it looks good to me
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#14
(Original post by the bear)
it looks good to me
ok thank you!
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#15
(Original post by Hornyrhino)
I think the light catches the district line from Victoria station and then goes from their to your eye. All dependent on Traffic of course. You know how London gets at Rush hour.
this is not what I needed
1
2 years ago
#16

I created an account just because I thought the previous answers perhaps didn't quite explain in full detail.

There are two reasons why light from the table is entering your eye.
The first (drawing A), is that no surface in the real world is truly flat. The surface is microscopically rough. The classical physics model with angles of incidence and reflection still applies. However, the "flat" surface is actually uneven, meaning their surface normals point in many directions. This effect is called diffuse reflection.

As some answers have previously described, light from the bulb can bounce off other surfaces in the room, eventually arriving on the table and reflecting into your eye (drawing B). However, the majority of the light entering your eye is through diffuse reflection. Light bouncing off other surfaces "adopts" the colour of the surfaces they are reflecting off of. For instance, if you shone a torch at a bright red wall, objects near the wall would receive a red hue.

Although light bounces off in all directions via the diffuse effect, light also bounces off as per your original drawing. When a surface is particularly glossy (metal, for instance), you will get a direct reflection of the light source (drawing C). This is the white sheen you see on glossy objects - it is called specular reflection.

In answer to your original question, the reason you can see the table is due to diffuse reflection. Secondary reflections also help, but not as much as diffuse reflections. Hope this helps.
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#17
(Original post by lb00218)

I created an account just because I thought the previous answers perhaps didn't quite explain in full detail.

There are two reasons why light from the table is entering your eye.
The first (drawing A), is that no surface in the real world is truly flat. The surface is microscopically rough. The classical physics model with angles of incidence and reflection still applies. However, the "flat" surface is actually uneven, meaning their surface normals point in many directions. This effect is called diffuse reflection.

As some answers have previously described, light from the bulb can bounce off other surfaces in the room, eventually arriving on the table and reflecting into your eye (drawing B). However, the majority of the light entering your eye is through diffuse reflection. Light bouncing off other surfaces "adopts" the colour of the surfaces they are reflecting off of. For instance, if you shone a torch at a bright red wall, objects near the wall would receive a red hue.

Although light bounces off in all directions via the diffuse effect, light also bounces off as per your original drawing. When a surface is particularly glossy (metal, for instance), you will get a direct reflection of the light source (drawing C). This is the white sheen you see on glossy objects - it is called specular reflection.

In answer to your original question, the reason you can see the table is due to diffuse reflection. Secondary reflections also help, but not as much as diffuse reflections. Hope this helps.
Thank you so so much this really helped I'm using this as revision also. I really understand it now
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