2009 Advanced Laboratories Conference Abstract Detail Page
Previous Page |
New Search |
||Using Pfund's method to find the index of refraction
||When our department introduced conceptually-oriented experiments in the freshman general physics laboratory, we soon found we also needed to revise the sophomore-level lab to give majors some simple lab exercises that would require reasonably sophisticated error analysis. Using Pfund's method to find the index of refraction of both a glass plate and a liquid provided an engaging exercise that gave students an excellent opportunity to practice these skills.
In our adaptation of Pfund's method, we use a flat and relatively thick glass plate that is sprayed on one side with white paint. A laser beam incident at 0°on the upper surface is diffusely reflected from a spot on the bottom painted surface. Rays from this spot travel back to the upper surface and pass through it as long as the incident angles are less than the critical angle. When the critical angle for the glass-air interface is reached the rays are reflected back and form a sharp ring of light on the bottom painted surface. Measurements of the diameter of this ring, together with the thickness of the glass allow the index of refraction of the glass to be calculated to within 1%. When a liquid layer is placed on the surface of the glass, the index of refraction of the liquid can be calculated also.
Download the Contributed Poster
||Session IX - Effective Experiments Poster Session
Helene F. Perry
Loyola College in Maryland
4501 North Charles Street