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The index if refraction is defined as a ratio of the average speed of light through a medium divided by the speed of light through a vacuum.
“n” is the index of refraction, “v” is the average speed of light through a medium, and vc is the speed of light through a vacuum. The speed of light is 3.00x 108 m/s in a vacuum.
All angles in optics are measured with respect to the line normal to the surface.
Because of the duality nature of light, it can be said that it travels in rays or waves. For this unit we are looking at the ray properties of light. The ray of light that hits a surface is called the “incident” ray. The angle the incident ray makes between the normal line and the ray called the incident angle. The Ray that bounces off a surface is called the “reflected” ray. The ray that travels to the other side of the surface is called the “refracted” ray. "To refract" means "to bend." The line separating the two mediums is called the “boundary.” “Medium” is another name for the material light travels through.
Snell’s Law mathematically states:
Where is on one side of the boundary and is for value on the other side on the boundary
Purpose: To use Snell's Law to determine the index of refraction (n) of a piece of glass and to use it to find the speed of light in that glass.
Materials: Laser level, protractor, plate glass, plain paper, pencil, data sheet.
Procedure: Check off each procedure upon completion.
The video instructions above can be found here, http://www.youtube.com/watch?v=z0zF9MtF_Z4
DRAW A GRAPH of the sin(θincident) vs sin(θrefracted) on the grid below.
The slope is the ratio of . The index of for the incident ray is air, n=1.00.
Use the graph to determine the index of the glass the light travels through and the average speed of the light through this glass. Show your work.
by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)