![]() ![]() ![]() Red light, least affected by refraction, appears along the arc's outer edge.īecause their speeds through water (and other media) are a set property of light, and since speed determines how much each is bent as they cross from air to water, they always fall in line as Roy G. Orange and yellow are refracted a bit less than violet and take up the middle of the rainbow. Violet (the most refracted) shows up at the bottom or inner edge of the arc. Rainbows form when billions of water droplets act like miniature prisms and refract sunlight. Shorter wavelength violet light interacts more strongly with the electrons and suffers a greater degree of refraction and slowdown. Red light interacts only weakly with the electrons of the atoms and is refracted and slowed the least. It's no surprise that each of those colors travels at a slightly different speed through a water droplet. ![]() Up to this point, we've been talking about white light only, but as we all learned in elementary science, Sir Isaac Newton conducted experiments with prisms in the late 1600s and discovered that white light is comprised of all the colors of the rainbow. Plop a pencil in a glass half filled with water and and you'll see what I mean. When light passes from one medium to another and its speed drops, it also gets bent or refracted. Free again, the beam now travels on until it slams into more atoms, gets their electrons vibrating and gets reemitted again. Light entering water immediately gets absorbed by atoms of oxygen and hydrogen, causing their electrons to vibrate momentarily before it's re-emitting as light. Why light slows down is a bit complicated but so interesting, let's take a moment to describe the process. Glass retards light rays to 124,275 miles/second, while the carbon atoms that make up diamond crunch its speed down to just 77,670 miles/second. When light crosses from air into water, say a raindrop, its speed drops to 140,430 miles a second (226,000 km/sec). While a beam's velocity through the air is nearly the same as in a vacuum, "thicker" mediums slow it down considerably. One of light's most interesting properties is that it changes speed depending on the medium through which it travels. Isn't there something faster? Einstein would answer with an emphatic "No!" Damn fast.īut when we look beyond the screen to the big, wide universe, light seems to slow to a crawl, taking all of 4.4 hours just to reach Pluto and 25,000 years to fly by the black hole at the center of the Milky Way galaxy. At this speed, the fastest known in the universe as described in Einstein's Special Theory of Relativity, light traveling from the computer screen to your eyes takes only about 1/1,000,000,000 of second. Ivy? When light passes through a vacuum it does so in a straight line without deviation at its top speed of 186,000 miles a second (300,000 km/sec). Considering that a human hair is 80,000-100,000 nanometers wide, visible light waves are tiny things indeed. A nanometer is equal to one-billionth of a meter. The cone cells in our retinas respond to wavelengths of light between 650 nanometers (red) to 400 (violet). Wavelength-the distance between two successive wave crests-and frequency, the number of waves of light that pass a given point every second, determine the color of light. Biv acronym, which describes the sequence of rainbow colors beginning with red, which has the longest wavelength, and ending in violet, the shortest. The familiar sequence is captured in the famous Roy G. ![]()
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