Waves

• Wave


  A transfer of energy through vibrations
• Sound waves are produced by the vibration of air molecules
• Purpose of a wave

  To transfer energy
• Different types of waves

  • Transverse
  • Longitudinal
  • Electromagnetic
  • Mechanical
• Properties measured in a wave

  • Amplitude
  • Wavelength
  • Period
  • Frequency
• Different types of electromagnetic waves

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


  When a wave bounces off a surface
• Refraction


  When a wave changes direction as it passes from one medium to another
• Diffraction


  When a wave spreads out as it passes through an opening or around an obstacle
• Reflection and refraction of sound waves
• Refraction of light waves through lenses and mirrors
• Mechanical waves


  Require a medium (solid, liquid, or gas) to propagate
• Electromagnetic waves


  Do not require a medium and can travel through a vacuum
• Electromagnetic waves


  • Light
  • Infrared
  • Ultraviolet
  • Gamma rays
• Transverse waves


  Molecules vibrate perpendicular to the wave motion, creating crests and troughs
• Longitudinal waves


  Molecules vibrate parallel to the wave motion, creating compressions and rarefactions
• Sound waves are the only longitudinal waves, while all other waves are transverse
• During an earthquake, S waves are transverse waves on the surface, while P waves are longitudinal waves underground
• Amplitude


  Maximum displacement of molecules from the mean position
• Wavelength (λ)


  Distance between two successive crests or troughs
• Period


  Time taken for one complete oscillation
• Frequency (f)


  Number of oscillations per second, measured in Hertz (Hz)
• Frequency and period


  Inversely proportional (f = 1/T)
• Wave speed


  Calculated as the distance of one oscillation divided by the time for one oscillation
• Electromagnetic waves


  Travel through a vacuum at the speed of light (approximately 3 x 10^8 meters per second)
• All electromagnetic waves are transverse, vibrating perpendicular to the direction of propagation
• Frequency and wavelength of electromagnetic waves

  Inversely proportional, meaning as frequency increases, wavelength decreases, and vice versa
• Colors of visible light

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
• Applications of electromagnetic waves

  • Gamma rays: cancer treatment and sterilization
  • X-rays: detecting broken bones and security checks
  • Infrared: thermal imaging, remote controls, optical fibers
  • Microwaves: satellite TV, mobile phones, microwave ovens
  • Radio waves: radios, RFID tags, communication
  • Ultraviolet: vitamin D production
• Microwaves from microwave ovens can cause internal heating and boiling of cells
• Infrared waves can cause skin damage or burns
• Ultraviolet radiation exposure can cause skin cancer
• 1. rays and gamma rays are ionizing radiation that can damage cells
• Protection methods


  Staying away from the source, reducing exposure time, and using shields or barriers
• Electromagnetic waves are used for communication, specifically in Wi-Fi, Bluetooth, and optic fibers
• Satellites use microwaves for communication regardless of their orbit
• Wave behaviors


  • Reflection
  • Refraction
  • Diffraction
• Wavefront


  Represented by arrows that indicate the direction of the wave, and straight lines called wavefronts that represent the crests of the wave
• Reflection


  The change in direction of a wave when it hits a surface
• The angle of incidence (I) is equal to the angle of reflection (r)</b>