A physics teacher created this video showing how to make a penny "disappear" by placing a Pyrex beaker over it and filling it up with water, asking why and how this illusion worked. On IO9, Esther Inglis-Arkell explains how the effect is achieved -- it's all down to the strange motion of light in water.
So when the penny is at the bottom of the beaker, there's only one sharp turn that the light from the penny has to make, from the pyrex dish to the air. The water-to-pyrex transition is comparatively mild, with little bending. The penny is distorted, but it's visible. When the wet penny is beneath the dish, but under another layer of water, the light also only has one sharp turn — back into the air at the end of its journey. Before that it only travels through water and pyrex, which have similar indices of refraction, and so it isn't bent much.
When the penny 'disappears,' though, it is taking two sharp turns, the massive turns between the pyrex and the air both at the bottom of the beaker and at the side. And, because of the way light bends, both turns are in the same direction, away from the eye of the viewer. Imagine the beaker full of water like an immense piece of rectangular carpeting on the concrete floor, and the light like a person on roller skates. (No, seriously, this will help.) The viewer is on the right side of this carpet. In order for them to see the penny, just under the bottom of the carpet, the light has to get from the penny to them.
Make a penny disappear with water
Gravitational waves are real, and scientists have detected them. In the video above, PBS Space Time explains the discovery by researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO). From the New York Times: A team of physicists who can now count themselves as astronomers announced on Thursday that they had heard and recorded the sound […]
Evil Mad Scientist Labs have released their latest set of nerdy Valentines ready for you to print, glue on cardstock, and use to win your true love’s heart.
“Bentonite Me Baby” is a brand of “detox clay” that you spread on your face, or eat, to rid your body of mysterious, nonspecific “toxins.” It is full of lead.
Hackers are people too. And sometimes, they’re the good guys. The fundamentals of hacking have created an entire new level to the security industry and one that you can totally dominate with this certification training course that’s 98% off now. To know how to protect something, you have to be able to see how it’s […]
Light used to just be one of two things: on or off. Simple as that. Either a flood of yellow or total darkness. Then the dimmer switch happened and you could adjust the brightness to meet your seductive needs and suddenly everyone looked a little better in the gentler light. And now your luminary universe […]
Projects will always need management. And now with the tech gold rush it feels like there are more projects than ever with fewer managers than there’s demand for. But it takes too much time and money to go back to school full time so luckily the Project Management Professional certification training course is now 96% […]