What is light

The photometry units are designed to take this into account, and therefore are a better representation of how "bright" a light appears to be than raw intensity. They relate to raw power by a quantity called luminous efficacyand are used for purposes like determining how to best achieve sufficient illumination for various tasks in indoor and outdoor settings. The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye, and without filters which may be costly, photocells and charge-coupled devices CCD tend to respond to some infraredultraviolet or both. Light pressure Main article:

What is light

The sun as it appears in X-ray light left and extreme ultraviolet light right. Light as energy Light is remarkable. We can complicate it by talking about interacting electric and magnetic fields, quantum mechanics, and all of that, but just remember--light is energy.

Light travels very rapidly, but it does have a finite velocity. In vacuum, the speed of light ismiles per second or nearlykilometers per secondwhich is really humming along!

What is light

It takes about two and a half seconds, for instance, for a radio communication travelling at the speed of light to get to the moon and back. You might find it interesting to remember, the next time you What is light a beautiful sunrise or sunset, that the sun itself actually dipped below the horizon eight minutes earlier--it takes that long for the light to reach the Earth!

And, of course, every newspaper article you ever read about astronomy will always include the required statement, "A light year is the distance light travels in one year at the speed ofmiles per second, about 6 trillion miles.

We should also highlight right up front that light is more generally referred to as electromagnetic radiation. Okay, we used a big word. It had to What is light sooner or later. But too often when we say "light" it is mistaken to mean "optical light," which is roughly the radiation visible to our eyes.

Visible light is a tiny portion of a huge smorgasboard of light called the electromagnetic spectrum. For our convenience, we break this smorgasboard up into different courses appetizer, salad, etc.

However, it is important to remember that they are all just light. There are no "breaks" and no hard boundaries in the electromagnetic spectrum--just a continuous range of energy.

Particles and Waves Physics experiments over the past hundred years or so have demonstrated that light has a dual nature.

In many instances, it is convenient to represent light as a "particle" phenomenon, thinking of light as discrete "packets" of energy that we call photons. Now in this way of thinking, not all photons are created equal, at least in terms of how much energy they contain.

Each photon of X-ray light contains a lot of energy in comparison with, say, an optical or radio photon. It is this "energy content per photon" that is one of the distinguishing characteristics of the different ranges of light described above.

Even though it is not strictly correct, it is hard not to think of a beam of light as a collection of little "light bullets" all strung together in a row. The "wave" model of light.

The other way of representing light is as a wave phenomenon. This is somewhat more difficult for most people to understand, but perhaps an analogy with sound waves will be useful. When you play a high note and a low note on the piano, they both produce sound, but the main thing that is different between the two notes is the frequency of the vibrating string producing the sound waves--the faster the vibration the higher the pitch of the note.

If we now shift our focus to the sound waves themselves instead of the vibrating string, we would find that the higher pitched notes have shorter wavelengths, or distances between each successive wave.

Likewise and restricting ourselves to optical light for the momentblue light and red light are both just light, but the blue light has a higher frequency of vibration or a shorter wavelength than the red light.

The colors of the familiar "rainbow" of visible light correspond to differing wavelengths of the light, here shown on a nanometer scale. The wavelengths get successively larger as one moves from left to right. Optical light runs from about to nanometers. Each range of light we have defined above corresponds to a range of frequencies or wavelengths of light vibrations.

These wavelengths are one of the primary indicators we use to describe light and spectra on a graph. Displaying a spectrum as a graph instead of just a color bar allows us to measure the light.

For instance, the "rainbow" of color shown in the figure above is what you see when you pass white light through a prism.Light has properties of both a particle and an electromagnetic wave but not all the properties of either. It consists of photons that travel in a wave like pattern.

Light is both a particle and a wave. Find out price list of LED products in India like bulbs, street lights, downlight & panel light, Wall light, Ceiling Light, Tube light, spot light and decorative lights from top brands like Philips, Osram, Havells, Wipro, Bajaj, Eveready, SYSKA, Oreva, Moser Baer, Surya, Charlston and Pharox.

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moving with effortless grace smooth stresses the absence or removal of all difficulties, hardships, or obstacles. a smooth ride. Find quick and healthy recipes, nutrition tips, entertaining menus, and fitness guides to help you make smart choices for a healthy lifestyle from Cooking Light magazine.

A accretion Accumulation of dust and gas into larger bodies. albedo Reflectivity of an object; ratio of reflected light to incident light. albedo feature.

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