Explain THIS one!

[Iamme]

This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

 

[BillHoyt]

This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

Oh, like this?

Answer: refractive index

Cheers,

 

[Iamme]

Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case.

 

[Dragon]

Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case.

Either or both of your eyes will be looking at a slight angle to the perpendicular. The "apparent depth" caused by the refraction of light at the boundary between the glass and the air will be less than without the glass - as seen in Bill's picture. When you look at a particular letter or word with both eyes your brain does its thing with the two different images and it appears to be raised. Does the effect disappear if you look straight down with one eye only?

 

[Ziggurat]

Does the effect disappear if you look straight down with one eye only?

Actually the effect won't disappear completely even with one eye, because parts of the letter will always be at an angle, and because your eye needs to focus on the apparent depth, not the actual depth. But it will certainly be more pronounced at a higher angle, and with both eyes.

 

[Upchurch]

Actually the effect won't disappear completely even with one eye, because parts of the letter will always be at an angle, and because your eye needs to focus on the apparent depth, not the actual depth.

Actually, with only one eye, there wouldn't be any depth perception, would there? I mean, you can get some depth perception with one eye due to context, but in this case, I think both eyes would be required to make the optical illusion of depth.

 

[Dr. Imago]

lamme,

Just a quick question. Don't have to answer if you don't want to.

But, how old are you?

Just curious.

-TT

 

[no one in particular]

Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case.

Index of refraction is not dependent on incident angle, only wavelength, density and chemical make-up. The index of refraction of most float glass (at 510nm) is approximately 1.5, while the refractive index of atmosphere is very near 1. The difference between the two media through which you were viewing the paper is what caused the apparent raise in the writing.

 

[Philip]

Actually, with only one eye, there wouldn't be any depth perception, would there? I mean, you can get some depth perception with one eye due to context, but in this case, I think both eyes would be required to make the optical illusion of depth.

As Ziggurat indicated, you also have some depth perception based on the distance to which your eye has to focus.

The virtual image of the writing under the glass is located closer your eye than the actual paper surface.

"3-D" movies that use the stereoscopic effect can cause eye strain because, even though the convergence of your left and right eyes on the two stereoscopic images is constantly changing, the distance to which the lenses of each eye focus remains the distance to the movie screen.

 

[hal bidlack]

lamme,

Just a quick question. Don't have to answer if you don't want to.

But, how old are you?

Just curious.

-TT

This post was reported, though I do not understand why. I find that this post does not violate the rules of the forum.

hal

 

[jj]

This post was reported, though I do not understand why. I find that this post does not violate the rules of the forum.

hal

Great GHU, doesn't Hal have enough to deal with?

 

[Iamme]

Third Twin---I am 13 and am in school and we are playing with pieces of glass. There... (wheeeee) just threw one across the room (tschhhhhhhhhh) Oops. Rats. I missed the teacher!

I'm 50.

I'm not married, so I don't have a life. I like experimenting with stuff. I write companies if I feel like I have a good idea. I was experimenting with 'filler' concoctions on a piece of glass, when I noticed this effect.

I'm curious why you ask. I presume the worst.

I've been around a little bit. Seen -54 on thermometer. Seen so much snow on the ground that road plows had to tier to prepare for the next snow. Operated a dry kiln (Guages/wet/dry heat) by myself. Smoked 3 packs of cigarettes a day. (Quit cold turkey). Got a one in State competition for baritone and trumpet.Worked in !07 degrees on World's largest nuclear power plant. Never have been to a war (good draft number.) Driven 1100 miles nonstop. Been on trains, jets and helicopter. Lived through world record rain fall. Lived through hurricane (Had to board up and flee). Got in national magazine. Got in national syndicated doctors health column in paper and have written in my thoughts on things to local editorial page. Write state commissioners, congressmen, etc. Been to a live tv show. I ran a water system (albeit small one). I've met all kinds of different people from different states. Shook hands with my governor. Talked to a famous racer. Collected found fossilized mastadon bones and fossilized shark teeth. Worked on hotrod type cars. Fixed most appliances (washers, dryers, water heaters, furnaces, etc.) Lived with thousands of cockroaches (and the games in destroying them). Witnessed two nude guys chasing themselves around the beach. Hitch-hiked/picked up hitch-hikers. Had Australian bicykling around the world stay over at my house. Ate rattlesnake/killed rattlesnakes. Built unusual house (2-story a-frame... I remodified blueprints to include dormer window/more space upstairs. Formed concrete. Framed buildings. Walked while beams to be poured up 6 stories. Stretched and seamed carpet (an endless list when it comes to remodeling , electrical, and plumbing.) I can't hardly sit still and enjoy learning new stuff. Does this help some?

 

[T'ai Chi]

This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

Hey Iamme,

How thick (tall) was the glass, and what type of paper document and ink (color) was used under the glass? I'd like to see if I can experiment around and duplicate the conditions on my coffee table.

My impressions before experimenthing is that as far as I know, a truly flat plate of glass does not magnify. To magnify an image, the glass must have a curved shape. But, since the text is being raised, ie. coming closer to you, I'd say it is being magnified, only slightly. I'd said that the pane is not exactly flat, or that some of the components that make up the glass are curved very slightly.

I'd probably try putting a 1" by 1" square under the glass, and then measure it's apparent dimensions and see if there is any change.

 

[BillHoyt]

Re: Re: Explain THIS one!

How thick (tall) was the glass, and what type of paper document and ink (color) was used under the glass? I'd like to see if I can experiment around and duplicate the conditions on my coffee table.

Someone buy this jerk an education. Woodini, we're talking about refraction, you nitwit troll.

 

[WildCat]

Refraction is what makes it so hard to shoot an arrow into a carp that is swimming underwater. Or a gar or dogfish (bowfin) for that matter. Or even to spear one.

 

[patnray]

T'ai Chi: Refraction can occur without magnification. With flat, parallel glass surfaces it just moves the apparent location of the image. Refraction is just a change in the direction of a light ray as it moves across the interface of materials with different refractive indicies (or, alternatively, in which the speed of light propagation is different).

 

[peptoabysmal]

Refraction is what makes it so hard to shoot an arrow into a carp that is swimming underwater. Or a gar or dogfish (bowfin) for that matter. Or even to spear one.

That's why some natives keep the tip of the spear underwater.

 

[T'ai Chi]

Re: Re: Re: Explain THIS one!

Someone buy this jerk an education. Woodini, we're talking about refraction, you nitwit troll.

You can't get under my skin Bill, ever.

If you disagree with what I say, just address that. There is no need to resort to insults etc.

And plus as an educator I'm more interested in encouraging experimentation, rather than giving one-liner answers.

 

[BillHoyt]

Re: Re: Re: Re: Explain THIS one!

You can't get under my skin Bill, ever.

If you disagree with what I say, just address that. There is no need to resort to insults etc.

And plus as an educator I'm more interested in encouraging experimentation, rather than giving one-liner answers.

Right. "Encourage experimentation." Why? So you can pop out your nitwit line about needing to test each instance? Each color? Each paper type? Each ink type? Holy piece of poseur poop. Cut the pose, peon.

You are the same troll you have always been. This time around you wish to pose as an educated troll. Knock it off, whodini. Dry up. Go away.

Your other choice is to listen and learn. Especially before spouting nonsense. To honestly be helpful to someone, know your subject matter first. Quit pretending to know until called out.

This is refraction, numbnit. Snell's law, stew. Color? Pah! Paper? Pah! Ink? Pah! T'ai Chi? Dry up.

Jeers,

 

[Beausoleil]

This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

In the first paragraph you seem to say that the writing seen through the glass looks raised over the paper seen through the glass - in which case the simple refractive index explanations given here don't work.

They work for the second paragraph, though, where 'seen through the glass' seems higher than 'seen not-through the glass'.