Robotics C++ Physics II AP Physics B Electronics Java Astronomy Other Courses Summer Session  

Films for the Humanities and Science

Video - Geometric Optics: Reflection, 57 minutes

 


What does a mirror tell us about light?

This cluster of 11 computer-animated video units delves into one aspect of light’s behavior—reflection.

Euclid’s geometric optics and his findings on the perception of distance and perspective lead to a discussion of the Law of Reflection—linking angle of incidence with angle of reflection—and the concepts of absorption, transmission, and diffuse reflection.

The principles involved with plane, concave, and convex mirrors are explained, including vertex, principle axis, center of curvature, radius of curvature, and virtual image. A group of “mirror equations” show how an object’s location can be determined using the laws of reflection.

 

1. The Idea of Light (06:31)

Since the early Greeks, philosophers and scientists have tried to describe the nature of light and explain the sense of sight. The notion of light as rays led to the study of optics and explanations of how light behaves.

2. Geometric Optics (06:32)

A modern understanding of light reflects its complex dual nature as both a particle and a wave. The Greek mathematician Euclid laid the foundation of geometric optics by describing the geometry of light rays which strike objects and reflect away from them.

3. Reflection (03:21)

An incident ray is a light ray which arrives at an object; a reflected ray is the ray that bounces off the object. The Law of Reflection states that when a light ray strikes a surface the angle of incidence will always equal the angle of reflection.

4. Reflection, Absorption, Transmission (03:20)

When light rays strike an object they can be reflected, absorbed, or transmitted. To understand reflection it is important to remember that absorption and transmission might be affecting the rays striking an object.

5. Diffuse Reflection (04:18)

Diffuse reflection occurs when rays strike rough surfaces, scatter in all directions, and return no organized pattern of light to the eyes. Diffuse reflection creates the patterns of relative lightness and darkness which our eyes interpret as different textures.

6. Object and Image (04:10)

The geometry of light rays can be used to explore the position of an object which, in turn, influences the magnification of the image that is formed and the attitude of the image. Geometric optics can determine whether an image is real or virtual.

7. Plane Mirrors (04:19)

Optical geometry can help predict the position and apparent size of a virtual image. Rays from an object can be drawn to extend backwards through a plane mirror to determine the position, magnification, and attitude of an image.

8. Concave Mirrors (08:07)

Concave mirrors can be engineered to create important optical instruments by using geometric optics. Parabolic reflectors are used in all kinds of applications where light and other forms of electromagnetic radiation are emitted and received.

9. Images in Concave Mirrors (05:16)

Because curved mirrors obey the rules of geometry, it is possible to predict the distortion of images by drawing ray diagrams. Depending on an object's position, it reflects in a concave mirror to form images in a variety of shapes and sizes.

10. Convex Mirrors (02:37)

Spherical convex mirrors form virtual images which are upright and smaller than the object. Mirrors like this are used to provide wide-angle views.

11. The Mirror Equations (07:30)

Incident rays and reflected rays obey the Law of Reflection. Geometry can be used to derive simple equations to determine the location of an image, its attitude, and the magnification of the image.