# Search results

1. ### Transparent Liquid Piezoelectric Material?

Hi All, I'm wondering if anyone is aware of a piezoelectric material that is both liquid and is transparent/colorless/ lower refractive index? Is there database online where I could compare these values? Google has not been kind to me:( Any help would be so appreciated.
2. ### OPTICS: How to solve a two lens system with the object in a medium?

Hi All, I need help determining focal length value in a two lens system. In the set up, the light source (object) is within a tube, a medium surrounds it with refractive index n1=1.52. The end of the tube is met with a curved convergent surface, the center of which is 0.635 cm away and focal...
3. ### How can time have a beginning?

I think it can really go either way.There is no way to say that our laws for the universe apply everywhere and at every time, because we simply haven't been there. At the same time,as DaveC4 said, there is no evidence that tells us that we should believe otherwise if our current scientific data...

5. ### Contact Lens: How to focus light 1mm away

So, I've been wondering. Anyone know what shape/prescription a contact lens would have to be in order for an eye to be able to focus on something 1mm away (assuming the distance of focus in the eye is around 4 cm)? Does it have to do with focal length of the lens?
6. ### How can time have a beginning?

I entirely agree with SystemTheory. There is simply no way of proving that the "Natural Laws" we have now are perfectly stable relative to all points in time and space. If you think about it, all the evidence we have about the universe has been gathered from only one minuscule point in that vast...
7. ### How to determine a lens width?

Simply curious if its possible. I'm not sure it is, which is why i'm wondering. What about if the object is a very small distance from the lens, like say 1 mm. Can you focus the image on the other side 3 cm away?
8. ### How to determine a lens width?

Ah, so it is also determined by the shape. However, i expect it would need to be a convergent lens type and assume it needs to be like a () shaped lens. The problem is however, that this equation can help find focal length but not describe how the lens itself will be shaped.
9. ### How to determine a lens width?

I am wondering... say an object was put directly on a lens and you wanted the projected image to focus at around 3 cm on the other side. How do you determine how wide the lens has to be? (please see attachment)
10. ### Light and Vision: Photon Direction

I think i get it. Thats pretty amazing. Thanks very much!!
11. ### Light and Vision: Photon Direction

Still not sure i understand. Let me try illustrating my understanding, and then correct me one how terribly misinformed i am. In the attachment i did a rough representation of what i'm talking about. If two points of emitting light are next to each other and near the eye, wont their photons...
12. ### Light and Vision: Photon Direction

How is it that light disperses from a point source (like a pinhole w/ a light shining through). From my understanding, photons disperses in all directions at all angles. So than how is it that an eye can differentiate that point from all the other points light around it (say there was another...