Waves in Air, Fluids and Solids

• There are two types of waves: transverse and longitudinal.
• A transverse wave is a wave for which the oscillations are perpendicular to the direction of energy transfer.
• A longitudinal wave is a wave for which the oscillations are parallel to the direction of energy transfer.
• Examples of transverse waves include electromagnetic waves and 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.
• P-waves travel through both solids and liquids.
• The time difference between emission and detection, alongside wave speed, are used to calculate distances in echo sounding.
• S-waves only travel through solids, not liquids.
• Echo sounding is a technique used to detect objects in deep water and measure water depth.
• High frequency sound waves are emitted, reflected and detected in echo sounding.
• The amplitude of a wave is the maximum displacement of a point on a wave from its undisturbed position.
• The frequency of a wave is the number of waves that pass a given point each second, measured in Hertz, Hz.
• The unit used for frequency is Hertz, Hz.
• A frequency of 200Hz means 200 waves pass a given point each second.
• Wave speed is the speed at which the wave moves or at which energy is transferred through a medium.
• Wavelength is the distance from a point on a wave to the same position on the adjacent wave, most commonly peak to peak or trough to trough.
• A wave transfers energy.
• Examples of uses for ultrasound waves include medical or industrial imaging.
• Seismic waves are produced by earthquakes and can travel through both P-waves and S-waves.
• P-waves and S-waves can travel through different mediums, with P-waves being able to travel through solids and liquids, and S-waves being able to travel through solids but not liquids.
• Sound waves travel through a solid by the particles in the solid vibrating and transferring kinetic energy through the material.
• Reflection is the word used to describe when a wave bounces off a surface.
• The frequency range of human hearing is 20 Hz - 20kHz, with 1kHz being equivalent to 1000 Hz.
• Ultrasound waves are defined as waves which have a frequency higher than the upper limit of human hearing, which is 20kHz.
• Wave Speed = Frequency x Wavelength Speed (m/s), Frequency (Hz), Wavelength (m)