You and Your Students!
Vicki Cobb, Education World Science Editor
Discover a new way to reveal a mirror image.
Everything we see is the result of light bouncing off objects into our eyes. In I See Myself, part of my Science Play series, I explain how a mirror reflects a perfect image. The source of the light coming from an object (including your face) is bounced perfectly off the shiny mirror and into your eyes; you see an accurate image reflected in the mirror.
Most non-shiny objects cant act as mirrors because they scatter light that strikes them in all directions and the reflection is fractured. There is, however, a way to make a non-shiny surface reflect a mirror image. All you have to do is change the angle at which you look at it.
Once you demonstrate how to do this, your students will all want to try it; it is likely that they will experiment with different surfaces all day long.
Hold the book with the shiny-surface cover up to your eye so that the book is parallel to the floor and your eye is looking along the surface of its cover. Hold it in such a way that about half your eyeball is covered by the end of the book. (Your pupil will be at the level of the books surface.) Tilt the surface of the book toward a brightly illuminated scene such as out the window on a sunny day or a colorful image on a computer screen. At the end of the shiny book covers surface you will see an inverted image of the object youre looking at.
Experiment with lots of different flat objects -- some shiny, some not. You will find that some are better than others at reflecting the scene but, amazingly, youll get mirror images from most of them. Even from a sheet of paper! If you look directly at that sheet of paper, you dont see an image reflected in it, but if you look very closely at the surface level of the paper, you will see the reflected image.
Non-shiny objects scatter most of the incident light that hits their surfaces in all directions. Most incident light comes from all directions, so light is always being scattered everywhere from everywhere. The exception is the incident light coming at an angle that just grazes the surface. All of this light is reflected perfectly at an angle almost parallel with the surface. This shows up as a mirror image at the far edge of the object, but you can only see it when your eye is in the right place, looking along the line of grazing incident light. At this angle just about every flat surface can reveal a mirror image.
Article By Vicki Cobb
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