Topic 4 - Waves

• Waves transfer energy and information, but not matter
• The two types of waves include longitudinal and transverse
• Transverse waves are waves that oscillate perpendicular to the direction of energy transfer.
• Longitudinal Waves are waves that oscillate parallel to the direction of energy transfer.
• Examples of transverse waves include electromagnetic waves, seismic s-waves
• Examples of longitudinal waves include sound waves and seismic p-waves
• The two parts of a longitudinal wave are called compressions and rarefactions
• The two parts of transverse waves are called peaks and troughs
• The amplitude of a wave is the maximum displacement point on a wave from its stationary position
• Wavelength is the distance from a point on a wave to the same position on the adjacent wave
• The frequency of a wave is the number of complete waves passing a point per second.
• The unit for requency is Hertz
• Wave speed is the speed at which energy is transferred through a medium
• Waves transfer energy
• Wave speed = Frequency x Wavelength
• The unit for wavelength is meters
• The period of a wave is the time taken for one complete wave to pass through a point
• Reflection is the word used to describe when a wave bounces off a surface
• The normal is a vertical imaginary line that is perpendicular to the boundary
• When light is REFLECTED off a boundary the angle of incidence is the same as the angle of reflection
• Refraction is the bending of light as it passes from one medium to another.
• When light is REFRACTED off a boundary the light speed and direction change when travelling through the new medium
• When light enters a denser material the waves slow down and bend towards the normal
• When light enters a less dense material the waves speed up and bend away from the normal
• Sound waves travel through a solid by the particles in the solid vibrating and transferring kinetic energy through the material
• 1kHz = 1000Hz
• The frequency range of a human being is 20Hz to 20,000Hz
• Sounds with frequencies above 20,000Hz are called ultrasounds
• Sounds with frequencies below 20,000Hz are called infrasounds
• Earthquakes produce both seismic s-waves and p-waves
• P-waves travel through both solids and liquids

  S-waves travel through solids only