Waves: Sound Waves
Waves: Sound Waves
Types of Waves
- Sound, like light, is a type of wave that allow us to interpret the world around us.
- Waves are essential for the transfer of energy without the movement of matter.
- There are two types of waves: longitudinal and transverse.
Longitudinal Waves and Sound
- Sound waves are an example of longitudinal waves.
- Longitudinal waves consist of several compressions and rarefactions.
- Compression refers to when particles in a medium are pushed closer together.
- Rarefaction refers to when particles in a medium are spread farther apart.
Properties of Sound Waves
- The wavelength of a sound wave is the distance between two consecutive compressions or two consecutive rarefactions.
- Frequency is the number of oscillations per second, measured in Hz.
- The amplitude of a sound wave determines the volume of the sound.
Speed of Sound
- Sound travels at different speeds depending on the material it is moving through.
- In air, sound typically travels at about 343m/s at room temperature.
- Sound travels faster in solids and liquids because their particles are closer together.
Sound Wave Reflection and Refraction
- Sound waves reflect off surfaces. This is how echoes are created.
- Sound waves also refract, or change direction, as they pass from one medium to another.
The Human Ear
- The ear is an example of an object which uses sound waves.
- The outer part of the ear, the pinna, collects the sound waves.
- The waves pass down the ear canal to the eardrum and make it vibrate.
- These vibrations are passed on to the fluid in the cochlea, which sends signals to the brain.
Sound and Technology
- Ultrasound waves are sound waves that have a frequency which is higher than humans can hear, typically above 20,000 Hz.
- They are used in medicine for scans, and in industry for measuring thickness and detection of defects.
- When these high frequency waves hit a boundary, they create a series of echoes that can be used to build up an image or detect flaws in materials.