http://flamecolour.wordpress.com/2011/08/25/visible-light/
The image above depicts the wavelengths that are visible to the naked eye. In the next tab, waves are discussed in relationship to hearing but the image was placed under optics to have a visual of what wavelengths are visible to the eye.
What are two kinds of lenses?
1. Concave
- the surface lens curve inward
- concave mirror causes light ray to converge
- concave lenses causes light rays to diverge
2. Convex
- the surfe bulges outward
- concave mirror causes light ray to diverge
- concave lenses causes light ray to converge
To converge means to form a real image by bringing it back to its focal point and to diverge means light scatters from its focal point.
Figure 1: Perfect vision
In the image above, it demonstrates how light travels to the retina in a person with perfect vision. Light in this case is focused on the retina.
Figure 2: Nearsightedness
The image above, demonstrates a person who is nearsighted which means that the light is focused in front of the retina. The use of divergent lens will help to correct nearsightedness.
Figure 3: Farsightedness
The image above, demonstrates a person who is farsighted which means that the light is focused outside of the retina. The use of convergent lenses will help to correct farsightedness by bringing the image back on the retina.
What is Snell's Law?
Snell's Law is used to describe the relation of the angle of incidence and the angle of refraction. Snell's law states that the ratio of the sines of the angles of incidence and refraction is equivalent to the ratio of the phase velocities in the media. The equation of Snell's law is as follows;
Θi = angle of incidence
Θr = angle of refraction
ni = index of refraction of the incident medium
nr = index of refraction of the refractive medium
Refraction is the beding of light as it crosses another medium. Incidence refers to the light ray hitting an object is perpendicular to it.
