Eye Definition and 263 Threads

Does the human eye have a "refresh rate"? This question probably seems ridiculous, but I have no background in physiology and I cannot find anything discussing it online or in my roommate's physiology textbook. I was wondering if anyone here knows whether the eye and brain processes...

Recently I had Lyme disease and had perhaps the most stereotypical bull's eye rash ever. All medical people I met wanted to see it, and called their friends/coworkers over, took pictures, etc. But the rash still has me confused about the biology of it. The shape itself doesn't seem to make...

Hi,my question is the following: Supposing that we light up the same surface of an optical system (the eye) by two different monochromatic lights (each one characterized by a wavelength and intensity): Can we predict the color that will be perceived by the eye? Thanks for your help.

This was really cool in-person. I didn't take the time to check my camera settings, so it didn't record as well as I'd have liked. I am calling it a crepuscular rainbow. This is a pic of sun beams (crepuscular rays) streaming through the clouds - into a mist of raindrops. So, this tiny...

how to know the defect of vision if power of accomodation of eye decrease or increase Homework Equations The Attempt at a Solution

http://heavens-above.com/PassSummary.aspx?satid=33442&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET It is losing height quite rapidly now, more than a kilometer per day.

the near point and far point of an eye are 35cm and 300cm respectively.what is power of lens so that the person can see objects at 25cm .with this lens what is the maximum distance he can see. f=xd/x-d p=1/f in m i could only solve the first part of the problem.p=1.14d...

http://en.wikipedia.org/wiki/Andromeda_Galaxy" http://en.wikipedia.org/wiki/Triangulum_Galaxy" http://en.wikipedia.org/wiki/Messier_81" I've only seen M31 with the naked eye. If I look at M33 through my 8 times 40 bino, then it doesn't look like something I could ever see with...

Hi, I was wondering about the following. A friend (biologist) once told me that looking a cat in the eyes shows aggression, whereas making eye contact with a dog creates a kind of connection or bond. However, a quick Google search seems to indicate that also in canines, direct eye contact is...

Assume I am standing in a desert at night (It's pitch dark). I have an opaque white object in front of me inclined at 45 degrees (see diagram). I now turn on a point light source next to me. http://img199.imageshack.us/img199/8945/lightt.jpg When I imagine the scene I feel I will be able to...

Homework Statement The diagram shows the eye of a person with normal vision looking at an object that is very far away. a) Determine the focal length of this persons eye. b) Later in this person's life, the focal length will change to between 2.1 cm and 2.3 cm. Will this person suffer from...

Many people I know advice me that doing eye exercises will help improve my vision and if I do them for quite some time, that I will not need glasses any more. Is this true? When I google this, all I get are advertisements.

hi there. there's an example in the book, but I'm having a little trouble here. Homework Statement Assume that the human eye can pick up as few as 9 photons/s in the visible range. Based on this, estimate the intensity of the dimmest star that can be detected by a night-adapted eye. What...

Homework Statement Could someone explain to me about the near point and the far point in the eye because I'm confused about the 25 cm for the near point and infinity for the far point. Also, like in problems like this: What eyeglasses would you prescribe for persons with the following...

When will the next comet apear for Earth viewers. I know that there is almost always a comet or two visable through a large telescope but when is the next one visable with the naked eye(I want to plan somthing import on that night.) . I wish i was around for comet Hale-Bopp but i was to young.

Last night there was something sharp in my eye and I messed around with it for a few minutes by blinking a lot popping my eyelid and rolling my eyeballs around. It didn't come out but when it got to a more comfortable position, I went to sleep, hoping it would automatically come out. Turns out...

Homework Statement Once dark adapted, the pupil of your eye is approximately 7 mm in diameter. The headlights of an oncoming car are 120 cm apart. If the lens of your eye is diffraction limited, at what distance are the two headlights marginally resolved? Assume a wavelength of 600 nm and...

Is the inside of the eye ball empty space? Or it is filled with oxygen?

http://news.yahoo.com/s/ap/20090110/ap_on_re_us/death_row_eye I can't believe they're going to execute him at all. If this isn't proof enough that he's insane, what would be? Here's his offender info: http://www.tdcj.state.tx.us/stat/thomasandre.htm

What biological reasoning explains the panoply of eye color in humans?

This has happened to me about 4-5 times over the last year or so, but at random it seems, one night I'll wake up in the middle of the night and not be able to open up my left eye because of this unbearable stinging sensation (it's always my left eye too). If I even try to pry it open a little...

I'm usually not too consciously aware of other people's body language. I don't want to read, then interpret, then act on the interpretation of someone's body language consciously. However, I've noticed something and I'm extremely curious as to what it means. Whenever I really want to create an...

Thought experiment: The 'perfect eye' (and a finite set of colours) Introduction: Human beings have trichromatic colour vision, our ability to distinguish different colours at different spectral frequencies, and wavelengths, of electromagnetic radiation, or combinations thereof, is...

Homework Statement Although the image in a television screen appears to change smoothly, it consists of 25 separate pictures every second. The production of a flicker free image is helped by: (i) PERSISTANCE OF SCREEN GLOW (ii) PERSISTANCE OF AN IMAGE ON THE EYE Explain how each of...

tell me how to perform this experiment and please post the figure of its apparatus.

Can laser eye surgery/anything fix cross eyes? 2 of my friends are cross-eyed and they're adults ty

I'm still comparatively a young buck at 22, but I have been afflicted by a few things that don't show up for most people until much later in life. The one I would like to focus on is vision because it's the most annoying to me. I don't get checkups too often so as best as I can recall, I had...

I've got a telescope (Meade DS114 -- reflecting, D = 114mm, F= 910mm, f/8) that I'm trying to get together again. We have several eye pieces still around -- H25mm, H12.5mm, SR4mm. We had a hard time locating objects (besides large things like the moon), so I'm wondering if I should try other...

have absolutly no idea where to put this but ill put it here My eyesight is something like +6.25/+6.50 Now the eye man (optomotrist?) said that they only make contact lenses that go up to +6. I was wondering why this is? Also why can't long sighted people have laser eye sugery? Is there...

Homework Statement A microscope has a converging lens (eyepiece) with focal length of 2.50 cm mounted on one end of a tube of adjustable length. At the other end is another converging lens (objective) with a focal length of 1.00 cm. When you place the sample 1.30 cm from the objective, what...

I'm having trouble finding information on why when you get far away from a piece of paper covered in yellow and blue dots (evenly spaced) the sheet eventually appears green. I know this has to do with color resolution but not much beyond that.

Homework Statement Under favorable circumstances the human eye can detect 1.0e-18 J of electromagnetic energy. How many 600-nm photons does this represent? (Modern Physics, Arthur Beiser, 6th Edition, Pg. 89) Homework Equations My answer is unreasonably low. My mistake is probably very...

Here is a product that claims it can teach you to speed read. http://www.infmind.com

[SOLVED] what's the diameter of a fly's eye? I'm a maths teacher and in a topic on units and 'big and small numbers', I've set my class various items to estimate, including the diameter of a fly's eye... Now it's driving me mad, I've spent hours googling to try to find out a reasonable...

My question is : Why do hypermetropian people not see reversed? According to wikipedia and many other sources, the light from a non reversed object arrives at the retina in the same sens, that is, non reversed. As we know, when interpreting images, the brain reverse the sens of the image on...

Photographing Magnetic Lines of Constant Scalar Potential http://www.sendspace.com/pro/dl/3hchd6 This post is intended as an introduction to my paper, Photonic Dipole Contours. I have been asked to address some deficiencies in my paper such as background information and prior work...

Hello everyone, Really struggling to answer a practice exam question on the eye, and was wandering if anyone could help, here's the question: "The unaided eye of a student has a power of 59.0D when viewing an object at infinity. When using her spectacle lens, the near point is 25cm from her...

1. Bond's usual gun of choice in every movie is a Walther PPK (except when he can get his hands on a machine gun which blows up more guys). A bullet like this has a mass of around 15g and leaves the gun at 288m/s. Calculate the kinetic energy in a bullet like this. 2.Aside...

How does the mind's eye 'see' in the absence of light? Imagine a large empty room with a dresser at one corner. You walk up to the dresser and open the top draw. You see a red book and a box of matches. You light the book on fire and throw it on top of the dresser. I assume you could all...

This is rather incredible. http://news.yahoo.com/s/afp/20080228/ts_afp/irelandbritainhealthoffbeat

Is it possible to calculate the diameter of the eye from front to back when you what kind of glasses the person needs? Like if someone needs -2 type of glasses is it possible to calculate the eye diameter? If not would it be possible to determine someones eye diameter by determine the closest...

Hi. I'm new to this forum and wondered if anyone can help with this problem I have understanding how vision works. In some ray diagrams of the eye it show the rays converging to a point on the retina and on some diagrams it shows them converging before the retina and arriving at the retina...

I found this: https://www.physicsforums.com/showthread.php?t=105106 But it the question was never really answered there. So I'd like to ask a *similar* question again. Are there any gases at STP, (without being "excited" or "liquefied"--see other topic, above) that are visible to the naked...

I once worked with a guy who had been hit in the head by lightning. As he described it, he was sitting on his porch and looking at a stop sign about a quarter-mile up the road. The last thing that he remembers - apparently at the moment of the strike - was the stop sign appearing to be...

Seems China is sending signals, but what is the message? http://news.yahoo.com/s/ap/20071130/ap_on_re_as/china_us_navy

[b]1. Homework Statement Q: How does our eye see virtual images, considering that no light is emmited by a virtual image and our eye can see anything only when light from it reaches the eye? Examples: Image by a plane mirror, concave lens, convex mirror and by convex lens and concave...

Homework Statement Suppose the lens in a human eye has far focal length equal to f[SIZE="1"]0 = .0405 m, for distant objects to be in focus. (a) An object K is 1.72 m from the lens. How much should the focal length change to focus on the object K? (b) What is the magnification ( = image size...

I reposted because I "bumped" this thread already with 2 replies and no one is answering.

Any opthalmologists or other occular medical experts out there? For decades, I've been making my own (usually elaborate) Hallowe'en outfits, including latex appliances. My avatar is one example of that. One thing that I've never been able to justify buying is costume contact lenses such as...

Hey guys. If it is clear out in your part of the World, look to the left of Delta and Alpha Perseus. There is a naked eye comet there. Look for a fuzz ball (it doesn't have a tail) that makes a point in a equallateral triangle with delta and alpha. It is beautiful in a telescope.