Discerning water temperature by color
Temperature sensitive LED illuminates the water in different
colors depending on the temperature of the water (red=hot, pink=warm,
blue=cold).The princple of the light reflection in
water is same as the princple of total internal reflection which is
important in fiber optics.
(hansa.de/ via Fresh News
Delivery)
RelInfo: Fiber Optics History
In 1870, John Tyndall, using a jet of water that flowed from one container to another and a beam of light, demonstrated that light used internal reflection to follow a specific path. As water poured out through the spout of the first container, Tyndall directed a beam of sunlight at the path of the water. The light, as seen by the audience, followed a zigzag path inside the curved path of the water.
This is a very famous experiment.
