P3 : ULTRASOUND
KEY FACTS ABOUT ULTRASOUND:
- Above human hearing range - above 20,000 Hz or 20 KHz
- Higher Frequency
- Produced by electronics
- Its used for ultrasound scans - pre natal (pregnancy) - used 'safe' (rather than X-Rays)
- All about reflection
- Partially reflected when they meet a boundary between two different layers of 'flesh' (soft tissue/bone)
- It works by: 1. Dectector measures time between reflections, 2. Work out how far away it is and builds up a picture electronically
- Used on injuries
- When an ultrasound is carried out between ultrasound 'pad' and skin - gel used, this helps ultrasound to 'enter' the body and not reflect off.
- Used for dental cleaning, the removal of kidney stones and jewllery cleaning --> vibrations caused by ultrasound break up the dirt or kidney stones by concentrating high energy waves at them.
- EQUATION: DISTANCE BETWEEN INTERFACES (LAYERS) = SPEED× TIME TAKEN
- NOTE : speed of waves × time taken = distance
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