09 light in focus
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09 light in focus

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09 light in focus 09 light in focus Presentation Transcript

  • Optics Theories Wave-Particle Duality Propagation Wave Speed Luminosity Illumination
  • The Theories of Light 1. Wave Theory • proposed by Christian Huygens in 1690 • considers light to be a wave propagating in ether (an assumed substance permeating all matter and space 2. Corpuscular or Particle Theory • proposed by Isaac Newton in 1704 • considers light as composed of tiny particles emitted by luminous object • cited formation of shadows as proof
  • The Theories of Light 3. Electromagnetic Theory • proposed by James Clerk Maxwell in 1860 • considers light as an electromagnetic (EM) wave, a transverse wave that is partly electrical and partly magnetic in nature 4. Quantum Theory • proposed by Max Planck in 1900s • considers light as being emitted by packets of energy called quanta • Einstein called each quantum of energy as photon
  • The Dual Nature of Light: A PARTICLE AND A WAVE • Since light has a dual nature, then it has two models or it can be presented and analyzed in two ways: as a ray and as a wave. • Ray Model of light is used to describe light as a particle and its behavior as a particle, and such is under the study of GEOMETRIC / RAY OPTICS. • Wave Model of light is used to describe light as a wave and its behavior as a wave, and such is under the study of WAVE OPTICS.
  • Measuring the Speed of Light 1. 2. 3. 4. 5. Olaus Roemer – 300 000 000 m/s Christian Huygens – 230 000 000 m/s Armand Louis Fizeau – 313 000 000 m/s Jean Bernard Leon Foucault – 299 796 000 m/s Albert Michelson – 299 799 600 m/s Accepted Value: 299 792 458 m/s ~ 300 000 000 m/s
  • The Rectilinear Propagation of Light RECTILINEAR PROPAGATION - property of light to travel in a straight path - one evidence of rectilinear propagation of light is the creation of a shadow
  • When can we see objects? 1. Luminous Object – object that can generate its own light 2. Illuminated Object – object that can not generate its own light but can still be seen because it can reflect light that it received from other sources
  • Types of Luminosity 1. Incandescence – emits light due to their hot bodies.
  • Types of Luminosity 2. Fluorescence – emits light by utilizing phosphors, which absorbs ultraviolet energy and releases visible light.
  • Types of Luminosity 3. Phosphorescence – a type of fluorescence where the emission of light persists even after external excitation.
  • Types of Luminosity 4. Gas Discharge – some gases can be made to produce light by passing an electric current through them.
  • Types of Luminosity 5. Bioluminescence – light produced in living organisms through chemical reactions between protein and oxygen.
  • MEASURING LIGHT Luminous Intensity (I) – strength or brightness of a source of light; measured in candela (cd) Luminous Flux (F) – rate at which light is emitted from a source and strikes the surface of a whole sphere; measured in lumens (lm) Illumination (E) – the amount of luminous flux falling on a unit area of a surface; measured in lux (lx)
  • Illumination and Distance: THE INVERSE SQUARE LAW • Illumination of light is inversely proportional to the square of the distance from the source • This means that the farther an object is from a light source, the lesser light falls on it. Examples: • If you move 2× away from a light source, you’ll receive only 1/4 of the original illuminance. • If you move 3× away from a light source, you’ll receive only 1/9 of the original illuminance.