SCI

• Wavelength


  Distance between two adjacent identical points in a wave
• Frequency


  Number of waves per second
• Crest


  • Highest point in a wave
• Trough


  • Lowest point in a wave
• Amplitude


  Distance between the rest position and the maximum displacement
• Period


  Amount of time to complete one cycle
• Types of Waves


  • Mechanical Wave
  • Electromagnetic Wave
• Mechanical Wave


  • Require a medium
  • Formed through vibrations
  • Examples: sound, seismic waves
• Electromagnetic Wave


  • Do not require a medium
  • Formed by moving charges
  • Examples: light, x-ray
• The Electromagnetic Spectrum
• Optics


  Branch of physics that deals with the behavior of light and other electromagnetic waves
• Light is an electromagnetic wave that can be perceived by the naked eye
• James Clerk Maxwell


  • Mathematically predicted the existence of electromagnetic waves in the 1860s
  • Calculated the speed of electromagnetic waves and found out that they travel at the same
• Heinrich Hertz


  Experimentally proved the existence of EM waves when he discovered how to make radio waves in the 1880s
• Maxwell's predictions and Hertz's experiment led to the conclusion that light is an electromagnetic wave
• Speed of light in vacuum: c = 299,792,458 m/s, 3.00 × 10^8 m/s
• Wavelength: 380 nm < λ < 700 nm
• Light


  • Has both particle- and wave-like properties
• Photons


  Discrete units that light travels in, like particles
• Photoelectric effect


  Electrons are ejected from a metal when light strikes the surface
• Light as a wave

  • It can bend around obstacles (diffraction)
  • It can exhibit interference when it interacts with other wavefronts
• Wavefront


  The locus of all adjacent points at which the phase of vibration is the same
• Ray


  • An imaginary line along the direction of travel of the wave
  • Perpendicular to wavefront

  
• Law of Reflection


  Occurs when light bounces off a surface

  
• Specular reflection


  • When light is reflected from a smooth surface

  
• Diffuse reflection


  • Scatter reflection from a rough surface
• The incident reflected and refracted rays, and the normal to the surface all lined up in the same place

  
• The angle of reflection is equal to the angle of incidence for all wavelengths and for any pair of materials

  
• Law of Refraction (Snell's Law)


  Occurs when light bends or changes in direction to another

  
• Light moves slower in more dense media and faster in less dense media
• Index of Refraction


  Ratio of the speed of light c in vacuum to the speed in the material

  
• For monochromatic light and for a given pair of materials, a and b, on opposite sides of the interface, the ratio of the sines of the angle θa and θb is equal to the inverse ratio of the two indexes of the refraction

  
• Cases of Refraction


  • Three

  
• The frequency of the wave does not change when passing from one material to another
• The wavelength in a material is less than the wavelength of the same light in a vacuum
• Total Internal Reflection


  Occurs when all the light incident to an interface is reflected back with none of it being transmitted even though the second material is transparent

  
• The index of refraction of material a must be greater than that of material b (na > nb) for total internal reflection to occur

  
• The angle of incidence must exceed the critical angle for total internal reflection to occur

  
• Critical Angle


  The angle of incidence for which the reflected ray emerges tangent to the surface

  
• Applications of Total Internal Reflection

  • A transparent rod with refractive