Embedded Files
Tutorial - How to perform
Tutorial - How to perform
Effect
Effect
A message is placed behind or underneath a transparent glass filled with hydrogel spheres.
After this set up ask the audience to read the message we have for them.
The Science behind
The Science behind
Aqua water beads when hydrated overnight, they have the same refractive index as water so are virtually invisible when covered with water. I like to put a beaker of beads on each bench and ask them to test the temperature, so they get a surprise when the feel the gel beads.
Hydrogels are virtually invisible in water.
A similar effect can be obtained with Pyrex and vegetable oil or glycerol as they have the same refractive index.
We only see things when is a refraction, when the light changes direction.
The message looks scrambled under the hydrated spheres because the light reflected off of the message is scattered in every direction by the water-filled hydrogels. It’s like trying to read through broken glass, in other words, impossible! When water is added to the dish, the light rays pass straight through the water and the spheres into your eyes without being scattered. This is due to the hydrogels identical index of refraction with the water. So, it seems like you’re looking through a cup of plain water and can easily read the message.
These demonstrations can be used to link this with invisibility cloak technology developments.
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