Dalena's+Light+Essay

__Light; It's Properties & Uses.__

Light is the name for the wavelengths of electromagnetic radiation that is visible to the naked eye. It doesn't require any material medium for it's propagation and its both a particle and a wave. It can travel in free space a speed of 3x10  8   metre per second and are transverse (meaning it moves, ossilating to the direction of energy transfer) in nature. Our eyes will interpret a different colour depending on the length of the wavelength of the light. The light we see with out eyes is a really very small portion of the electromagnetic spectrum, and there are many types of lights that the human eye cannot detect, as illustrated by the diagram. Electromagnetic radiation with a wavelength between 380nm and 760 is detectable by the human eye and perceived as visible light.



Infra-red light is electromagnetic radiation that and is outside the scope of visibility because the wave length is longerat about 300 micrometres. It is used in television remotes, night vision, in meteorology, imaging, as a deliberate heating source, in communications, to detect trends in energy exchange and many more. Ultraviolet light has a wavelength shorter than visible light but longer than xrays. Depending on the wave length, UV light can be used for different purposes. It can be used to eliminate insects, in forensic analysis, to disinfect water and surfaces (especially for equipment in medical or biological laboratories), in light therapy, to cure printer inks to name a few.

Shining a beam of white light into a triangular prism made of glass will disperse the light into different colours. This act, of refractive indices differing for each wavelength of light produces an effected called dispersion. The longer wave lengths can be seen as red and the shorter as yellow. The colours we see are causes by differing light wavelengths. This diagram illustrates dispersion.



Visible light refers to the electromagnetic wave lengths that are visible to the human eye. The uses for which are to illuminate some place dark or to display something unseen. It can also be used in light therapy and the reflection of light shows us the reflection in mirror. One may think that scientists know the answers but light continues to suprise them. Its at once both mysterious and obvious.

Bibliography

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 Wave Properties of Light. 2011. //  Wave Properties of Light  // . [ONLINE] Available at: [|__http://csep10.phys.utk.edu/astr162/lect/light/waves.html__] . [Accessed 22June 2011]. =====

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 What Is a Light Source?. 2011. //  What Is a Light Source? // . [ONLINE] Available at: [|__http://www.lightsources.org/cms/?pid=1000166__] . [Accessed 22June 2011]   =====

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 Properties of Light. 2011. //  Properties of Light  // <span style="font-family: Helvetica Neue,Helvetica;">. [ONLINE] Available at: [|__http://www.tulane.edu/~sanelson/geol211/proplight.htm__] <span style="font-family: Helvetica Neue,Helvetica;">. [Accessed 22June 2011]   =====