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Light is Energy

The term “Light” can describe many different forms of electromagnetic energy. Light is Energy. Electromagnetic Spectrum. increasing frequency. increasing wavelength. Electromagnetic Spectrum. Long wavelength --> small frequency Short wavelength --> high frequency.

bertille-marley
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Light is Energy

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  1. The term “Light” can describe many different forms of electromagnetic energy. Light is Energy

  2. Electromagnetic Spectrum

  3. increasing frequency increasing wavelength Electromagnetic Spectrum Long wavelength --> small frequency Short wavelength --> high frequency

  4. Spectrum of White (Visible) Light

  5. The Visible Spectrum COLOR FREQUENCY (Hz) WAVELENGTH (nm) • Red 4.04.8 x 1014 700-630 • Orange 4.85.1 x 1014 630-590 • Yellow 5.1-5.4 x 1014 590-560 • Green 5.4-6.1 x 1014 560-490 • Blue 6.1-6.7 x 1014 490-450 • Violet 6.7-7.5 x 1014 450-400

  6. ElectromagneticSpectrum In increasing energy, ROYGBIV

  7. Or is it a Particle acting like a wave? Light is an electromagnetic wave

  8. Nature of Light Like sound waves, light exhibits properties of waves. These are diffraction, reflection, refraction and interference. In addition, light waves also exhibit dispersion and polarization. Unfortunately, Light cannot be completely described by the Wave theory.

  9. Nature of Light Light has particle-like properties as shown by Einstein's Photo-electric effect. Light is said to travel in photons or small packets of NRG. The Explanation  Dual-nature of light

  10. Diffraction of Light • Particle • Wave

  11. The Principle of Reflection The Angle of Incidence = The Angle of Reflection

  12. Mirror Image Image formation from a plane mirror Image appears at a distance equal to the object distance. Image is the same size as the object.

  13. Refraction The bending of light upon entering a medium with with a different density. A light wave will speed up or slow down in response to a changing medium.

  14. Beach Party Imagine lines of people rushing from the parking lot to the sandy beach. People can run faster on pavement than in the sand. Pavement Sand

  15. Beach Party Pavement Sand

  16. Beach Party Pavement Sand

  17. Beach Party Pavement Sand

  18. Beach Party As people enter the sand, they slow down. Pavement Sand

  19. Beach Party Pavement Sand

  20. Beach Party Pavement Sand

  21. Refraction Light waves, like people waves, will slow down and bend or refract.

  22. Refraction Incident Angle As a wave enters a piece of glass its velocity slows down and the wave is bent towards the normal line. As it exits it will speedup and is bent away from the normal line. Air Glass medium Surface Normal

  23. Dispersion Light of different frequencies is refracted by different amounts Red Light (lower frequency, longer wavelengths) is bent the least. Blue Light (higher frequency, shorter wavelengths) is bent the most. Refraction is Dispersive

  24. The Beauty of Dispersion and Refraction

  25. Rainbows

  26. Wave Speed v = l Sound (in air) ~ 344 m/s Light (in vacuum) ~ 3x108 m/s What is the wavelength of a sound wave which has a frequency of = 1000 Hz? 344 m/s = l 1000 Hz l = 344m/s/1000/s (Seconds cancel) l = 0.34 meters 1/3 of a meter in size, 1000 of them each second!

  27. Wave Speed c = l Sound (in air) ~ 344 m/s Light (in vacuum) ~ 3x108 m/s What is the wavelength of a radio wave with = 94.1 FM? AM kHZ = 103 Hz FM MHz = 106 Hz 3x108 m/s = l (94.1 x 106 Hz) l = 3x108 m/s / 94.1 x 106 /s l = 3.2 meters 3 meters in size, 94,100,000 of them each second!

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