P12: wave properties

• Wave


  Something that transfers energy, not matter
• Types of waves


  • Transverse waves
  • Longitudinal waves
• Transverse waves


  • Peak
  • Trough
  • Wavelength (distance between two peaks/troughs)
  • Amplitude (distance between peak/trough and equilibrium line)
• Longitudinal waves


  • Compressions (areas of high density)
  • Rarefactions (areas of lower density)
• Frequency


  How many waves pass a certain point per second, measured in Hertz
• Period


  Time taken for one full cycle of a wave
• Wave speed


  Equals frequency times wavelength
• Speed of electromagnetic waves in a vacuum is 3 x 10^8 m/s
• Transverse waves


  Travel fastest through gases
• Longitudinal waves


  Travel fastest through solids
• Light entering a denser medium

  Angle of refraction is less than angle of incidence
• Light reflecting off a surface

  Angle of incidence equals angle of reflection
• Critical angle


  Angle of incidence at which total internal reflection occurs
• Sound is a longitudinal wave
• Transverse representation of sound wave

  • Pitch (frequency)
  • Volume (amplitude)
• Ultrasound


  High frequency sound wave
• Bats use ultrasound to track prey and avoid obstacles
• Humans use ultrasound to detect fish and measure distances
• 1. waves (longitudinal) and S-waves (transverse) are used to study the Earth's interior
• 1. waves can travel through solids and liquids, S-waves can only travel through solids
• The Earth's outer core is liquid, as S-waves cannot travel through it
• 1. waves are refracted when passing from the mantle to the liquid outer core, creating a shadow zone