Make Invisibility, VISIBLE - With the light science demonstration and light science experiment for grades 9+ based on the Rochester Cloak!
The Invisibility Kit allows you to use a set of 4 lenses, a meter stick and a little bit of math to make ordinary objects disappear before your very eyes! Making use of the refractive nature of light, the lenses cause light to bend around objects, rendering them INVISIBLE! Its a light science experiment your students will not forget!
Invisibility happens when an object that “should” bounce light into your eye does not. The object is present, but no light bounces from it into your eye, so it appears to “not be there”. Now, you can simply cover an object and no light from it will get into your eye, but that is not really invisibility in the way that we like to think about it. What we’d really like, is to be able to see around and behind the invisible object, as though it were not there at all. That’s a little more tricky.
One way to achieve invisibility is by bending light. Bending light is called refraction, and its actually something we see all the time. Check out that duck up there. Is it really split in half? No. It is not split in half. But it sure looks like it’s split in half. What’s going on?
When light travels from one medium (air) into another (water, glass, plastic, etc.) it changes speed. This change in speed causes the light to “bend”. When light bends, it appears to come from somewhere other than where the object actually is. That’s what’s happening with the duck up there! Instead of bouncing off the duck directly into our eyes in a straight line the way light usually does, the light travels from outside the water, into the water where it bounces off the duck, through the water and then back out of the water and THEN into our eyes. All that traveling in and out of the water causes the light to bend in such a way that what we end up seeing is a duck whose bottom half has shifted and looks as though it’s been cut in half!
THE ROCHESTER CLOAK
It turns out that by using a set of 4 lenses, scientists at the University of Rochester have figured out a pretty cool way to make light bend around objects so that all you can see is what’s behind them! Let’s go ahead and replicate it with your kit to make some things invisible. Instructions and mathematical explanations included!