P3.1.2 Ultrasound Flashcards
What is the human range of hearing?
20 Hz to 20,000 Hz.
What frequency are ultrasound waves?
Above 20,000 Hz.
What happens when ultrasound waves meet a boundary between two substances with different densities?
They are partly reflected back. The remainder of the ultrasound waves continue to pass through.
What does a detector placed next to the source of the waves do?
Detects the reflected waves and measures the between the wave leaving the source and hitting the detector.
How is the distance traveled by the ultrasound wave calculated?
Distance = Time x Speed
Speed = Distance / Time Time = Distance / Speed
How can ultrasound waves be used in industry?
They can be used for quality control procedures to check manufactured objects, such as railway tracks and oil pipelines, for damage or defects.
How can ultrasound be used in medicine?
Prenatal scanning - Ultrasound images are used to check that the foetus is developing normally and to take measurements of its growth.
Scanning organs such as the liver for signs of disease.
Kidney Stones - High frequency ultrasound waves focused at a kidney stone cause it to vibrate, breaking it into small enough pieces to pass out in the urine.
How is an image created using ultrasound?
Computers can combine many ultrasound reflection readings to produce a detailed image from them.
Give a benefit of Xrays compared to ultrasound.
Xrays have a shorter wave length than ultrasound and so they can produce higher quality images than ultrasound scans - very helpful when looking for small fractures in bones.
Give a disadvantage of Xrays compared to ultrasound.
Xrays are ionising so they damage living tissue and the DNA within cells - especially rapidly dividing cells of a foetus. Ultrasound waves are not ionising so they can be used to scan foetuses safely.
