Electromagnetic Waves

• Electromagnetic waves travel at the speed of light in vacuum
• Electromagnetic waves can be reflected, refracted, and diffracted

  
• Electromagnetic waves


  • Transverse waves - E, B, and propagation direction are perpendicular
  • Possess the same qualities as light
  • Are all forms of radiation
  • Are essentially light but invisible

  
• William Herschel


  German astronomer responsible for the discovery of Uranus in 1781, experimented on different inherent temperatures of colored light using sunlight bent through a prism, discovered temperature to be highest just below the red-colored light, formerly known as Calorific Rays (or Heat Rays) and now widely known as INFRARED
• Johann Wilhelm Ritter


  German chemist who discovered ultraviolet rays, a hundred years after infrared, noticed that silver chloride was transformed faster from white to black when it placed at the dark region of the Sun's spectrum (just after violet light), energy-carrying wave also follow wave phenomena like reflection, refraction, interference, and diffraction
• James Clerk Maxwell


  Studied EM Waves for many years, described induction of magnetic fields from changing electric fields, demonstrated induction of electric fields from changing magnetic fields, predicted that repetitions of the inductions create an oscillation, these oscillations carry energy in the form of heat (radiation)
• Heinrich Hertz


  First detected and generated EM Waves after Maxwell's prediction in 1887, classified EM Waves as Transverse Waves, discovered that E and B are perpendicular to one another and perpendicular to the direction of the wave's propagation
• The right-hand rule can be used to determine the direction of the electric field, magnetic field, and propagation direction of an electromagnetic wave

  
• EM Wave Generation


  Electric field produced by the alternating current (AC) circuit shifts its direction downward, the earlier produced fields move perpendicular the axis where the fields oscillate, magnetic field induced by the movement of the field-carrying charges
• Relationship of an oscillation's wavelength and frequency

  c = λf
• Ranges of wavelengths and frequencies

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays

  
• There is an Electromagnetic Spectrum Song
• Visible Light


  The range of EM radiations that can be perceived by our eyes

  
• Frequency and Wavelength Trends

  ↑ λ ↓ f

  
• Max Planck


  • Theoretically resolved the classical problems of blackbody energy emissions
  • Calculated for the Planck's constant h which spearheaded and revolutionized Quantum Physics
  • Discovered that light's frequency and energy are not infinitely directly proportional
  • Theorized that light energy can be quantized through particle-wave identity of light
• Ultraviolet Catastrophe


  In Newtonian (Classical) Physics, black bodies are said to have an infinitely increasing relationship of its energy absorbed as the frequency increase infinitely
• Quantized Energy


  • E = nhf
  • Energy of light can be calculated in multiples of integer n. An initial evidence that light behaves as a particle unlike the popular notion that it is solely a wave (electromagnetic). n = 1, 2, 3, ….

  
• Einstein's Idea of Photons


  Through Photoelectric Effect, Einstein proved that light waves can interact with matter as particle-like energy packets called photons

  
• ROYGBV


  • Is the arrangement of visible light for increasing wavelength

  
• VBGYOR


  • Is the arrangement of visible light for increasing frequency and energy
• Seeing Color


  • Light rays travel in straight lines from the source
  • When it hits an opaque object, some light is absorbed while the rest is reflected off
  • If the material is transparent, light rays pass through easily
  • If the object is translucent, some light can pass through and some are reflected

  
• White Light


  • An object's color appear depending on the color of light that it reflects
  • A white object would reflect all seven colors
• Object's Color


  • The color an object appears depend on the colors of light that it reflects
  • For example, a red book only reflects red light
• Color Addition


  • White light can be split up to make separate colors. These colors can be added together again
  • The primary colors of light are red, blue, and green
• Color Addition


  • A pair of purple trousers would reflect purple light (or red and blue, as purple is made up of red and blue light)
• Complimentary Colors


  • There are two combinations of colors that can reflect white light
  • RED and CYAN = WHITE = R + (G + B)
  • GREEN and MAGENTA = WHITE = G + (R + B)
  • BLUE and YELLOW = WHITE = B + (G + R)
• Color Subtraction


  The ultimate color appearance of an object is determined by beginning with a single color or mixture of colors and identifying which color or colors of light are subtracted from the original set