1 - 1 Light in Everyday Life What is the difference between...

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1 Light in Everyday Life What is the difference between energy and power? A watt is a unit of power , which describes the rate of energy use. A power of1 watt means that 1 joule of energy is being used each second: 1 watt = 1 joule/s What are the four ways in which light and matter can interact? Emission : When you turn on a lamp, electric current flowing through the filament of the light bulb heats it to a point at which it emits visible light. Absorption : If you place your hand near a lit light bulb, your hand absorbs some of the light, and this absorbed energy makes your hand warmer. Transmission : Some forms of matter, such as glass or air, transmit light. That is, they allow light to pass through them. Reflection : A mirror reflects light in a very specific way, similar to the way a rubber ball bounces off a hard surface, so that the direction of a reflected beam of light depends on the direction of the incident (incoming) beam of light Sometimes reflection is more random, so that an incident beam of light is
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This note was uploaded on 04/07/2010 for the course POLITICAL PS260 taught by Professor Craigcobane during the Spring '10 term at Uni. Iceland.

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