Visible Spectrum

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Visible Spectrum
From longest to shortest wavelengths the colors
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ROYGBIV
Red, 650-700 nm
Orange, 580-649 nm
Yellow, 575-579 nm
Green, 490-574 nm
Blue, 455-489 nm
Indigo, 425-454 nm
Violet, 400-424 nm
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Electromagnetic Spectrum
Shortest wavelength Greatest frequency
Longest wavelength Lowest frequency
All wavelengths of light travel at the same
speed, the speed of light.
Wavelength and frequency are inversely
proportional.
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Particle Description of Light
(when the light given off is a stream of
particles - electrons - instead of light waves)
Photoelectric Effect
- emission of electrons from a metal when light
shines on the metal
Example much like a coke machine that requires
an exact coin before it will give back a coke.
Exact energy must be put in for electrons to be
given off.
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Max Planck

• German scientist
• studied light given off by hot objects
• didnt think waves were continuous
• thought energy was given off in packets he called
  quantas
• Quantum minimum amount of energy that can be
  lost or gained by an atom

Relationship E h?

• E energy in joules
• frequency
• H Plancks constant

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Albert Einstein

• expanded on Plancks theory
• introduced idea that electromagnetic radiation
  has a dual wave-particle nature
• each particle carries a quantum of energy
• light acts like waves, but can also be like a
  stream of particles
• Photon a particle of electromagnetic radiation
  having zero mass and carrying a quantum of energy

E1 photon (h) (?)
-where h Plancks constant, ? frequency and E
is the energy of 1 photon in joules