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
Apple released this lovely new commercial featuring Carl Sagan reading from his magnificent 1994 book Pale Blue Dot: A Vision of the Human Future in Space, now available as an audiobook. This surprising partnership spurred Adweek to interview my friend Ann Druyan, Sagan’s wife, collaborator, and creative director of the Voyager Golden Record, about being […]
The Action Lab took a maglev gyroscope and placed it inside a sealed chamber to see what happens to a levitating gyroscope in a vacuum. A lot of people took issue with the experiment’s setup and explanation, but it’s interesting nonetheless. He responded to those concerns: Hi everyone! I see a lot of comments that […]
Shocking footage, taken from a nearby aircraft, shows a jetliner spraying its appalling chemical payload into our skies. Traffic 12 o'clock pic.twitter.com/g5QjlQ5v8z— Airplane Pictures ✈ (@iLove_Aviation) June 19, 2017
Even though credit cards now feature an EMV chip for securing transactions, they still have to include the magnetic strip for compatibility with older point of sale systems. Because of this, there’s no way for the chip’s new security capabilities to protect against card skimmers in the wild.How do you protect yourself from legacy-technology-induced fraud? […]
As the old saying goes, “You should sit in meditation for 30 minutes every day. Unless you are too busy, in which case you should meditate for an hour.” Since most of us have an endless list of things to do and people to see, carving out quiet time can feel impossible, especially when most […]
The Bragi Dash Truly Wireless Smart Earphones are far more than your run of the mill Bluetooth earbuds. While the earpiece design makes these earbuds ideal for exercise and activity, and passive noise cancelling is conducive to a more serene listening experience, these buds go well beyond just playing music.First of all, they can actually […]