Ch 18 5 sources of light

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Ch 18 5 sources of light

  1. 1. Ch 18-5 Sources of Light Objects that give off their own light are LUMINOUS
  2. 2. Incandescent Light <ul><li>Light produced when a object gets hot enough to glow </li></ul><ul><li>Electrons flow throw a filament in the bulb, when it gets hot it emits light. </li></ul>
  3. 3. Fluorescent Light <ul><li>Emits light by causing a phosphor to steadily emit photons. </li></ul><ul><li>Essentially is it a string of collisions changing wave lengths into visible light. </li></ul><ul><li>More energy efficient than incandescent bulb </li></ul>
  4. 4. Laser Light <ul><li>Laser is a beam of coherent light </li></ul><ul><li>It is emitted when excited atoms emit photons. </li></ul><ul><li>Coherent light does not spread out so it has a constant intensity. </li></ul><ul><li>Can be used to cut, heat materials. Carry information or make measurements. </li></ul>
  5. 5. Neon Light <ul><li>Neon lights emit light when electrons move through a gas or a mixture of gases in glass tubing. </li></ul><ul><li>Different gases or mixtures give off different light colors. </li></ul>
  6. 6. Sodium-Vapor Light <ul><li>As electric current passes through a sodium-vapor bulb it ionizes the gas mixtures. As the mixture warms up it’s heats causes the sodium to change from solid into a gas. </li></ul><ul><li>The move electrons into higher energy levels, when the electrons return to the lower energy they release energy. </li></ul><ul><li>Very energy efficient and very bright. </li></ul><ul><li>Often used as parking lot and street lights. </li></ul>
  7. 7. Other Lights <ul><li>Tungsten-Halogen light - like an incandescent light but uses a tungsten filament and last longer than incandescent. </li></ul><ul><li>LED – Light Emitting Diode – they have a low energy consumption, often many are used together to produce a bright light. </li></ul>

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