Light can come from many sources—light bulbs, candles, fires, flashlights, smartphone screens, the sun, etc. No matter from whence it originates, however, all light behaves in the same manner. One principle of light is that it always reflects off a surface in a straight line. The exceptionally easy little experiment outlined below can be used to demonstrate how light reflection is affected by the surface off of which it reflects.
Shine A Light
All you’ll need for this experiment is a square of aluminum foil about and a light source. Carefully cut your foil using the knuckle-destroyer built into the packaging, making sure to avoid wrinkling, tearing, or otherwise damaging the foil—you need a flat, smooth piece for the first part of the experiment to work properly.
Find the shiny side of the foil (hint: it’s the shiny side) and, with your light source shining overhead (hint: overhead lights work great), peer into the shimmering depths of the foil. You’ll see your reflection looking back at you. It won’t be as clear as a mirror’s reflection, but it is a reflection nonetheless.
The light reflects back in straight lines, giving you a (relatively) clear image in the foil’s smooth surface.
Part II: The Crumpling
Now, take that same piece of aluminum foil and crumple it into a loose wad. Keep it loose enough that it can be uncrumpled without being totally ruined. Flatten it out as best you can, then look again at the surface of the shiny side.
¿Donde es su reflexión? By crinkling the foil, you’ve filled the surface with ridges and seams that reflect the light away from you. It’s still reflected in straight lines—because light is always reflected in straight lines—but those straight lines are now angled in countless directions because of the crinkles.
- 365 Simple Science Experiments with Everyday Materials, E. Richard Churchill, Louis V. Loeschnig, Muriel Mandell, and Frances Zweifel, 1997. ISBN 978-1884822674