Optics ! Interested

[jyoticlub]

Hi everybody,

 

I am new to this site and switched here just to have a answer at my questions.

My question to you intellectuals is just a bit silly,

I want to know " Why the things which are far away from our eyes look small and also in definite ratios"

 

I hope you understood my question.

 

Jyoti

http://www.jyoticlub.jaijyoti.com

[swansont]

Because s = r* theta (arc length = radial distance * angle)

[jyoticlub]

Yes, I have got my answer.

Thanks everybody but still if you can please explain me in details

 

Thanks again

[□h=-16πT]

It's the nature of the (convex) lens in our eye: if objects are beyond the focal length of the eye then they appear smaller than they actually are. You can find this in any book treating optics.

[J.C.MacSwell]

Hi everybody' date='

 

I am new to this site and switched here just to have a answer at my questions.

My question to you intellectuals is just a bit silly,

I want to know " Why the things which are far away from our eyes look small and also in definite ratios"

 

I hope you understood my question.

 

Jyoti

http://www.jyoticlub.jaijyoti.com[/quote']

 

Let's say you are in your sailboat and you are 1 mile from the dock and you have a buddy in an identical sailboat 2 miles from the dock.

 

The dockmaster sees your boat as twice the percentage of his panaramic view as your buddy's, while your buddy is at twice the distance or radius of that panoramic view.

[Johnny5]

I want to know " Why the things which are far away from our eyes look small and also in definite ratios"

Jyoti

 

Years ago' date=' I answered this exact question, by drawing a ray diagram, and then working out the answer mathematically.

 

If you double the distance between you and a tree, the tree shrinks in size by a factor of 2.

 

Let me see if i can find a diagram on google, which leads to the right conclusion.

 

I can't find the answer, but lets see if i can explain.

 

Suppose that you are standing on the ground, and there is a giant california redwood a distance R away from you.

 

So you can draw a triangle, which goes from the base of the tree into your eye, and from the top of the tree into your eye.

 

Now, from a physics standpoint, here is what actually happens. Photons emitted from the surface of the tree go outwards in all directions. That's why everyone can see the tree no matter where they are standing. But the image that your brain ends up processing, is based upon only the actual specific photons that actually enter your eye.

 

These photons travel for all intent and purpose, in a straight line from the atom on the tree which emits them, directly to your eye, and so the sides of the triangle are drawn as straight lines.

 

For the sake of simplicity, suppose that the triangle is a right triangle.

 

The actual height of the tree will be denoted by h, and the base of the triangle will be denoted by R.

 

eye)______________________________| h

R

 

Let the angle the hypotenuse, and side R make with your eye be denoted by

 

[math] \theta [/math]

 

 

Now, suppose you move closer to the tree, to a distance R/2.

 

eye)_______________| h

r=R/2

 

Even though the actual height h of the tree does not change, the tree will now appear larger, you know this is true based upon sensory perception.

 

Your question is merely why.

 

The way that your question gets answered properly, requires that you learn something about lenses, and what they do, because there are lenses in your eye.

 

Let me see if i can find a relevant article on lenses.

 

Here is a site which allows you to play with the positions of an object, and a lens, and then shows you the image height after the rays pass through the lens. This is the kind of thing you need to learn, in order to have the answer.

 

Regards

[jyoticlub]

Johnny 5,

It was great to have a such an explanation to my question .Though I know all about lenses and the structural and functional components of human eye, I was not able to clarify my doubt that

 

The cylindrical convex lens in our eye functions just as the simple lenses and as the object is at a greater distance from us (infinity), It must form the image which is diminished ,But How can our eye adjust that the much farther the object , the much smaller it goes and as it comes close , it goes bigger ?

 

 

If you can , You may take idea posted by swansont

 

 

"Because s = r* theta (arc length = radial distance * angle) "

 

 

Thanks very much !

 

Jyoti