Properties of Waves

• Waves


  A disturbance that moves through particle movements caused by vibrations/oscillations. Waves do not carry particles but it carries energy from one place to another.
• Mediums


  A medium is the material through which a wave travels. Mediums for waves to occur include solids, liquids, and gases. Mechanical waves require a medium to travel (e.g. sound). Electromagnetic waves can travel through empty space with no particles called vacuums (e.g. light).
• Transverse Waves


  A type of wave that moves the medium at a right angle to the direction that the wave travels. It has a crest, the highest peak of the waves, and a trough, the lowest point of the wave. Examples include visible light, radio waves, and X-rays.
• Longitudinal Waves


  A wave that displaces the particles of the medium parallel to the direction the wave travels. Compression is where the particles are closest together and Rarefaction is where the particles are further apart. Examples include sound, ultrasound, seismic p-waves.
• Surface Waves


  A combination of transverse and longitudinal waves. Energy travels along the surface of the medium. The wave occurs between two media and travels slowly but can cause severe damage. Examples include ocean waves, ripples in water, and seismic waves.
• Amplitude


  The max distance waves move away from the rest position
• Wavelength


  The distance between two corresponding parts of a wave.
• Frequency


  The number of complete waves that pass a given point in a certain time
• Speed


  The distance waves travel in one unit of time. Speed is measured in meters per second
• Relationship between wavelengths and frequency


  As the wavelengths increase the frequency decreases and vice versa.
• P Waves

  • Longitudinal waves
  • The particles in the rocks vibrate back and forth so as they pass through a material, they cause that material to stretch and squash repeatedly, like an accordion.
  • Travels through any type of matter, whether solid, liquid, or gas. Sometimes, P-waves go all the way through the Earth because they can pass through all of its layers!
• S Waves

  • Causes the particles in rocks to vibrate from side to side in a repeating cycle.
  • The vibration is always perpendicular to the direction the wave actually travels in
  • Can only travel through solids, they cannot pass through liquids or gases, unlike P-waves. This difference has actually helped geologists to map the inside of the Earth
• Speed of P-waves vs S-waves

  • P-waves travel through the Earth faster than S-waves, meaning they are recorded by seismometers before S-waves
  • It also means P-waves can warn of incoming S-waves, which tend to do more damage. The arrival of the P-waves a few seconds earlier gives people time to get shelter under their desks or in doorways