Waves for Detection and Exploration

About

• Ultrasonic waves have a frequency >20kHz 
• Can't be heard by humans
• When wave meets a boundary between 2 different materials it is partially reflected
• Measuring how far away a boundary is → time taken for ultrasonic waves to return to detector 
  

Uses:

• Detecting defects in materials without cutting into them
• Medicine → pre natal scanning, detection of kidney stones and tumors, images of damaged ligaments and muscles

Echo sounding - using ultrasonic waves for detecting objects in deep water and measuring the depth of water 

Ultrasound pulse in the water is reflected back when it hits the surface

Time between pulse being sent and reflection being detected is used to calculate the distance travelled:

DISTANCE = SPEED X TIME

Speed of sound in water is 1500m/s

Two types of seismic waves produced during an earthquake:

P - waves → Primary Waves

S - waves → Secondary Waves

P - waves:

• Longitudinal waves
• Travel at speed of sound - 6-13 km/s
• 2x faster than S - waves
• Travel at different speeds through solids and liquids

S - waves:

• Transverse waves
• Can't travel through liquids
• Travel at 3.5-7.5 km/s