Download The Index of Refraction and Snell`s Law

The Index of Refraction and Snell’s Law
In a vacuum, electromagnetic waves (including visible
light) travel at the speed c =________________________.
However, in other materials, light travels slower than this.
The factor by which the speed is reduced is called the index
of refraction, n. Each material has its own index of
refraction, and this number can be looked up easily.
n
c
v
Example.
Determine the speed of light in fused quartz glass, if its
index of refraction is 1.46.
Snell’s Law
When light travels from one medium to another where the
speeds are different, the light bends or refracts, just like
water waves do in the ripple tank.
Source: http://image.tutorvista.com/content/human-eye-colourful-world/atmospheric-refraction.jpeg,
accessed January 12, 2010
If the wave travels from a medium where the speed of light
is faster to where it is slower (less dense to more dense,
n1<n2), the wave will bend toward the normal line (see
diagram). If it travels from a more dense to a less dense
medium (n1>n2), the wave will bend away from the normal
line.
Source: http://media-2.web.britannica.com/eb-media/91/96591-004-959BC455.gif. accessed January 12,
2010
Snell’s Law relates the angle of incidence and the angle of
refraction in the two different media.
n1 sin 1  n2 sin 2
Example.
Determine the angle of refraction for light traveling from
air (n=1.0003) into water (n=1.33) at an angle of incidence
of 30 degrees and 60 degrees.
For the Snell’s law lab you will do, the apparatus is sort of
like this:
http://demo.physics.uiuc.edu/lectdemo/scripts/demo_descri
pt.idc?DemoID=281 , accessed January 12, 2010