4th

• 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


  • Medium required
  • Formed through vibrations
• Electromagnetic Wave


  • Medium not required
  • Formed by moving charges
• Optics


  Branch of physics that deals with the behavior of light and other electromagnetic waves
• Light


  An electromagnetic wave that can be perceived by the naked eye
• James Clerk Maxwell


  Mathematically predicted the existence of electromagnetic waves in the 1860s
• James Clerk Maxwell


  Calculated the speed of electromagnetic waves and found out that they travel at the same speed as light
• 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: 299,792,458 m/s, 3.00 x 10^8 m/s
• Wavelength of visible light: 380 nm < λ < 700 nm
• Light


  • Travels in discrete units like particles called photons
  • Travels as a wave
• 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


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


  • Specular Reflection
  • Diffuse Reflection
• Law of Refraction (Snell's Law)


  The ratio of the sines of the angle of incidence and the angle of refraction is equal to the inverse ratio of the two indexes of refraction
• 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
• 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
• Critical Angle


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


  • An imaginary line perpendicular to the surface at the point of incidence
  • All angles are measured with respect to the normal
• Interface


  Boundary between two different medias
• Dispersion


  • Occurs when light separate or spreads out into a spectrum of colors
  • Arises due to differences in the speed of different wavelength of light
• The speed of light in vacuum is the same for all wavelengths, but the speed in a material is different for different wavelengths
• The index of refraction of a material depends on the wavelength of light
• Light of longer wavelength has greater speed than light of shorter wavelength
• Electronics


  A branch of Physics that deals with the emission and behavior of electrons in electronic devices
• Electrical Circuit


  • A continuous loop where electrons can flow
  • Basic elements: power supply, conductor, load
• Circuit Diagram


  A schematic representation of an electrical circuit showing its components and how they are arranged