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# Factor's that affects the focal length of a lens watch

1. I am trying to find Factor that affects the focal length of a lens. So far i have found:
The distance from the light bulb to the lens
The material the lens is made from
The curvature of the lens
The thickness of the lens
The only thing i can't really explain how these factors would affect the focal length of a lens, so it would be great if someone could explain.
Thanks
2. Power = 1/f = 1/v - 1/u

if alter one then alter all, eg if alter u will alter f
material affects optical density, so power of lens, how much it bends the light
curvature - how curvy the lens is, so how much the light is bent
thickness, how much is bent

how much light is bent affects power, which in turn affects focal length (v)

hope this helps
3. The distance of the object from a lens doesn't affect its focal length. The focal length is fixed by the other factors mentioned. It's the focal length that affects the image distance for a given object distance.
Check out "The Lensmaker's Equation" for the factors that affect the focal length of a lens.
You have them all there except one. Do not include "object distance" in the list.

http://en.wikipedia.org/wiki/Lens_(optics)
http://en.wikipedia.org/wiki/Lens_(o...r.27s_equation
4. Does anyone know how these would affect the focal length of the lens:

The refractive index of the material will affect the focal length.
The curvature of the lens

Thanks
5. (Original post by Anon606)
Does anyone know how these would affect the focal length of the lens:

The refractive index of the material will affect the focal length.
The curvature of the lens

Thanks

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