30 Jun, 2013
PRESENTATION: The formation of an image in a simple optical system depends on the characteristics of the system and the position the object occupies with respect to the system’s poles and focal points, according to the Laws of Gauss.
- Determining the Thickness and Refractive Index of a Mirror, Ahmet Uysal, Phys. Teach. 48, 602 (2010)
- Virtual Mirrors, Thomas B. Greenslade, Phys. Teach. 48, 26 (2010)
INTRODUCTION: A concave (or converging) mirror possesses a reflective surface which curves inwards. Concave mirrors reflect light to make it converge at a focal point. Concave mirrors show different images depending on the distance between the object and the mirror. They are called “converging” mirrors because they tend to collect the light incident on them from far away, deflecting the parallel rays of light towards the focus. Two of their main uses are as telescopes and make-up mirrors.
OBJECTIVE: To find the focus and check the formation of images at different distances from it.
MATERIALS: Concave mirror.
SETUP: The mirror is placed so that its main axis is horizontal. Using the experimental method with parallel rays, the distance of the focus, F, can be determined, and, consequently, the centre of curvature, C.
EXPLANATION: A ray parallel to the axis hits the mirror and is reflected to the focus. Another ray leaving the object goes to the focus and on hitting the mirror, bounces off parallel to the main axis. The point where these rays cross will determine the position, size and nature of the image. However, if the object is at the focus and the above procedure is followed, then we will see that the two rays are parallel. This means that they cross at infinity and cannot, therefore, form an image.
CONCEPTS: main axis, centre of curvature (C), focus (F), vertex, object distance (S), image distance (S’).
- PHYSICS CLASSROOM
- PHYSLET (Spherical Mirrors)
- PHYSLET (Reflection)
- WAKE FOREST UNIVERSITY
- Tipler P.A. Física, Reverté, 2010.
- Serway R.A, Jewett J.W., Física, Thomson-Paraninfo, 2010.
- Valero M., Física Fundamental I, Norma, 1986.
- García C., Física II, PIME, 1985.
STUDENTS 2012-2013: Antonio Barreiro, Sergio Dafonte, Samuel Iglesias.
LINK pdf STUDENTS (in Spanish):