emr/usgsweb/examples/exLightbulb.jpg
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| Light: The Basics | ||||||||||||||||||||||||||||||||||||||||||||||||
| Whats is light? | ||||||||||||||||||||||||||||||||||||||||||||||||
| Light is a form of energy that has many applications to the world we live in. It is viewed and measured in various ways according to its application. We find light everywhere in our lives. From sunrise to sunset, literally. When the sun rises in the morning you can feel the change in temperature, usually it gets warmer. The heat that you feel is coming from the energy from the sun. The energy travels to the earth as light. This explains the heat that you feel when there is light. The light that travels from the sun to your eye allows you to see and view the colors around you. The light from the sun is also absorbed by plants as energy. This allows the plants to go through the process of photosynthesis and grow. Light travels in either waves or photons. Waves are ripples that look similar to sound waves. Photons are little packets of energy. Photons of different colors have different energies. | ||||||||||||||||||||||||||||||||||||||||||||||||
| Incandescent Light Bulb | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Image from http://resourcescommittee.house.gov/subcommittees/ emr/usgsweb/examples/exLightbulb.jpg |
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| How is light measured? | ||||||||||||||||||||||||||||||||||||||||||||||||
| Watts | ||||||||||||||||||||||||||||||||||||||||||||||||
| Incandescent Light Bulb | ||||||||||||||||||||||||||||||||||||||||||||||||
| Contrary to popular belief, light is not measured by Watts. This is believed primarily because incandescent light bulbs are labeled in Watts. However, a watt is the amount of energy that is used in the light bulb. A watt does not measure the illumination or intensity that a given light portrays. The amount of energy in the light, the given watt amount, is only a small portion of the actual amount used to create light. For example, from a 60-watt light bulb the light you see is illuminated by 3-watts of energy. The majority of watts in a light bulb is used as heat, not light. | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Image from http://www.discount-internet-store.biz/bettymills/subdir20/61305.htm | ||||||||||||||||||||||||||||||||||||||||||||||||
| Illiumination | ||||||||||||||||||||||||||||||||||||||||||||||||
| Photometer | ||||||||||||||||||||||||||||||||||||||||||||||||
| The illuminescence of light is measured in a lux (metric system). A lux is the amount of light it takes to illuminate 1 meter squared in lumens. The amount of lux necessary depends uon the brightness necessary to illuminate a given room. For example older people might need a greater quantity of lux to adjust their eyes properly. | ||||||||||||||||||||||||||||||||||||||||||||||||
| When measuring the intensity of light, you refer to a photometer. A photometer is an instrument that is used to determine a lights intensity, illumination, or brightness. An advanced photometer can measure the light intensity as specifically as of wavelengths of light. Chemist use these to study patterns and things that they cannot see with there own eyes. Most photometers though are used for such things as telescopes, lighting, and in cameras. | ||||||||||||||||||||||||||||||||||||||||||||||||
| Lumens | ||||||||||||||||||||||||||||||||||||||||||||||||
| A Lumen is used to describe the quantity of light produced. The amount of lumens in a light bulb is approximatly 15 times the amount of waats used. For example, a 60 watt light bulb has 880 lumens. | ||||||||||||||||||||||||||||||||||||||||||||||||
| Back to ChemX homepage | ||||||||||||||||||||||||||||||||||||||||||||||||
| Fluorescent lights | ||||||||||||||||||||||||||||||||||||||||||||||||
| Color | Light and Chemical Reactions | Black Lights | ||||||||||||||||||||||||||||||||||||||||||||||
| Halogen Lights | ||||||||||||||||||||||||||||||||||||||||||||||||