30 Jun, 2013
PRESENTATION: A spherical mirror is a reflective surface defined by its radius of curvature, R, and with an image focus that coincides with its object focus at an intermediate position between its pole and its centre of curvature. If the latter is to the left of the pole, then it is a concave mirror. A convex mirror is the opposite case.
- The Dizzying Depths of the Cylindrical Mirror, Alan J. DeWeerd and S. Eric Hill, Phys. Teach. 43, 90 (2005)
- Spherical mirror images of dynamic objects, Terrence P. Toepker, Phys. Teach. 30, 252 (1992)
INTRODUCTION: The Dutch mathematician and astronomer Willebrord Snellius (Snell) (1581-1626) devoted himself to the study of geometrical optics. Snell managed to measure the angles formed by rays that are incident on the separating surface between two media, and those formed by refracted rays. He used these measurements to formulate the law of refraction, also known as Snell’s Law, which was later developed by Descartes.
OBJECTIVE: To show the reflection of a spherical mirror.
MATERIALS: concave and convex mirror, light source, power supply.
SETUP: After connecting the light source to the power supply, ensure that the room where the experiment is being carried out has the right level of lighting, that is, a level that will not interfere with the result of the demonstration. Finally, place the mirror and the light source in such a way that all the rays are incident on it in parallel to its optical axis (follow the same procedure when doing this with the concave mirror).
EXPLANATION: When the parallel ray of light hits the surface of the spherical mirror, it is reflected and passes through the image focal point that coincides with the object focal point, which is located half way along the radius.
CONCEPTS: reflection, refraction, Snell’s laws, Fermat’s principle, principle of light propagation, spherical mirror, image focus, object focus.
- R. Serway, Física, Mac Graw Hill, 2010.
- P. Tipler, Física para la Ciencia y la tecnología, Reverté, 2012.
- H. W. Farwell, The Optical Surfaces of Descartes and Huygens, AJP 9, 255-263, 1941.
- G. F. Herrenden-Harker, Caustics by Reflection in a Concave Spherical Reflectting Surface, AJP 16, 272-284, 1948.
- Allen Newell and Albert V. Baez, Caustic Curves by Geometric Construction, AJP 17, 145-147, 1949.
STUDENTS 2012-2013: Felipe Rodríguez, Efrén Rodríguez, Lois Liste, Lara Suárez
LINK pdf STUDENTS (in Spanish):