Exploring Structure Using Waves (HT only)
- Sound waves can be used to analyse structures that are hidden from direct observation
- Examples of the use of sound waves
- Echo sounding used by shipping to detect the ocean floor
- Ultrasound used to look inside the human body
- Ultrasound crack detection to find cracks in rail tracks
- Reflection seismology to detect oil and gas underground
- Seismic activity (Earthquakes) can be used to investigate the structure of the Earth
- The properties of a substance that allow the detection of hidden structures are:
- Reflection
- Absorption
- Transmission
- The speed of sound in the substance
- Each type of substance will produce different amounts of reflection, absorption and transmission
- Each type of substance will also transmit a sound wave at a specific speed
- Sounds will travel faster in solids than liquids and sound travels faster in liquids than gases
- Certain structures will reflect a proportion of the sound wave and transmit the rest
- Some substances will absorb sound waves with very little reflection
- By detecting the amount of sound reflected and the speed of the wave the hidden structure can be identified
