In this chapter i have learnt many new and amazing things about Images with Lenses.
As you may noticed that there are 2 things that affect the characteristics of the images formed. The kind of lens where there are Converging and Diverging and the location of the object. As you know, you can find an images characteristics by drawing ray diagrams. Just like you did with Converging and Diverging mirrors. In order to find an image, you know that there has to be two light rays to locate the image. Basically everything i have noted down here; you already know. The only difference is that with mirrors your considered reflected rays, and with Lenses you consider Refracted Rays.
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Refracted Ray - It is the change or bending in direction of light when it travels from one medium to another.
This is a perfect example of a refraction.>>
List of Examples for Refraction < Click to watch
If you want to know how to draw ray diagrams for lenses, it is important to know how the incident and Emergent rays are related to each-other. The Emergent Ray is the ray that leaves the lens, being refracted as it goes from the lens back into the air.
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This is an example of an emergent ray.As you can see here, when an incident ray goes through a thick lens the emergent ray is refracted. If the ray goes through a thin lens, you don't really see a difference.
Another amazing way to understand how lens work is, by using a rectangular prism.
^^From this picture above, an incident ray directed at a rectangular glass prism undergoes two refraction's. The first is at air- glass boundary, as the ray enters the prism, and the second is at the glass- air boundary when the ray emerges from the prism. If we look at this prism in a 3-Dimensional way, there are two sides of the prism. And when light passes through these two boundaries, they are parallel to each other. All in all the sideways displacement depends on the thickness of the prism.
Light through a Prism click on this link to see how light works with prisms!!
How to Locate the Image in a Converging Lens
Basically there are three imaging rules for a converging lens.
As you can see here, to find an image through a Converging Lens, you have to follow three simple steps: Ray 1 goes parallel to the principal axis and refracts through the principal focus. Ray 2, goes through the secondary principal and is refracted parallel to the principal axis. And ray 3, is not needed but if you want an accurate image, it would go through the optical center and continues its way on straight without being refracted. If you are wondering why Ray 3 goes right through the Optical center, it is because the middle part of the lens acts like a very thin rectangular prism with no noticeable sideways displacement.
You can investigate images in a converging lens by placing a candle at a distant greater that 2F', you can locate an image of this source by moving a paper screen back and forth oh the other side of the lens.
These are different characteristics of an Image in Converging Lenses
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| Object between F' and 2F' Larger Inverted Beyond 2F Real  Object beyond 2F'
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| Object at 2F' - Same size - Inverted - At 2F - Real Quick Video to learn how to locate an image in converging lens When an object is located beyond 2F', the image is smaller that the object and is between 2F and F. As you gradually move the object closer towards the lens, the image gets larger and larger.When it comes to a point where the object and the image is the same size, the object will be located at 2F'; the image is now laced at 2F. When it keeps continuing the object will be between 2F' and F', you get a larger image than the object. REMEMBER !! - For all these image positions, the image is always inverted and real. THAT WAS ALL FOR CONVERGING !! DON'T WORRY , WERE NOT DONE HERE!! .jpg) How to Locate the Images in Diverging Lenses The imaging rules for a diverging lens are quite similar to the converging lens. The only difference is that the light rays do not actually come from the principal focus; they only appear to.  As you can see here Ray1 goes parallel to the principal axis and is refracted as if it had come through the principal focus. Ray 2 appears to pass through the secondary principal focus and is refracted parallel to the principal axis. And Ray 3 passes through the center continues straight through on its path. All of the rays never meet, but what diverging lens do is they extend the refracted rays backwards. Where those rays meet is where a new image is formed. Click on this video to learn how to locate images in Diverging Lens Remember that Diverging Lens always produce the same image characteristics no matter where the object is placed. It is always , smaller, upright, virtual and on the same side of the lens as the object! IN SUMMARY
If your serious about learning more things on Diverging Lens and Converging Lens. Please visit these sites.
http://www.guesspapers.net/621/refraction-of-light-and-optical-instruments/ Watch these videos as well. !! :D http://www.youtube.com/watch?v=PjuDjJzdf8w http://www.youtube.com/watch?v=OSUGRvYwxw8 http://www.youtube.com/watch?v=nyEa6oB59_Y .jpg)  Kevin Fernando |
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