Gizmo

• Light


  A form of energy visible to the human eye that is radiated by moving charged particles
• Light from the sun


  An electromagnetic phenomenon that originates from the accelerated motion of electric charge
• Light or electromagnetic radiation


  • May be viewed as a wave in an abstract electromagnetic field
  • May be viewed as a stream of massless particles called photons that move at a constant speed of 300,000 km/s in vacuum
• Electromagnetic spectrum


  • Radio Waves
  • Microwaves
  • Infrared Waves
  • Visible Light
  • Ultraviolet (UV) Rays
  • X-rays
  • Gamma Rays
• Visible light

  Represents a narrow group of wavelengths between about 400 nm and 750 nm
• Radio Waves


  • Longest electromagnetic waves used in MRI, RFID, and radio/TV broadcast
• Microwaves


  • Extremely high frequency waves used in cooking, cellular phones, and satellite broadcasting
• Infrared Waves


  • Referred to as heat waves, used in various applications like remote controls and physiological diagnostics
• Visible Light


  • Defined as radiation visible to human eyes, with colors ranging from red to violet
• Ultraviolet (UV) Rays


  • Have wavelengths from 10 m to 400 mm, categorized as UVA, UVB, and UVC
• X-Rays


  • Have wavelengths from 0.01 m to 10 m, used in medical imaging and airport security
• Gamma Rays


  • Have wavelengths less than 0.01 mm, used in cancer treatment and sterilization
• Reflection


  Involves the absorption and re-emission of light by means of complex electromagnetic vibrations in the atoms of the reflecting medium
• Refraction


  Refers to the change in direction of the wave at a boundary where the wave passes from one medium into another
• Index of Refraction


  • If the second medium is more optically dense than the first medium (nb > na), the refracted ray is bent towards the normal (θb < θa)
  • If the second medium is less optically dense than the first medium (nb < na), the refracted ray is bent away from the normal (θb > θa)
• Optics


  • Geometric optics
  • Wave optics
• Geometric optics


  • Light is modeled as a ray
• Wave optics


  • Light is modeled as a wave
• two major aspects of geometric optics

  • Reflection and refraction
• Normal


  A line perpendicular to the boundary of the two media at the point of incidence
• Angle of incidence (θ)

  The angle between the incident ray and the normal
• Angle of reflection (θ)

  The angle between the reflected ray and the normal
• Angle of refraction (θ)

  The angle between the refracted ray and the normal
• Laws of Reflection

  • Reflection involves the incident ray, reflected ray, and normal lying in one plane
  • The angle of incidence is equal to the angle of reflection
• Laws of Refraction


  • It involves the incident ray, reflected ray, and normal lying in one plane
  • Refraction involves a change in direction of light passing from one medium to another
  • The laws of refraction describe the behavior of light at boundaries between different mediums
  • The relationship between the index of refraction and the angle with the normal is described in Snell's law, named after the Dutch astronomer and mathematician Willebrord Snell