Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • Free Essays • My Term Papers • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Physics ultrasound ultrasound 1. The echo method is used by ships to measure the depth of water below a ship. The instrument used is called fathometer. Why are ultrasound used instead of the ordinary sound? (a) The ultrasound will not be confused with the ordinary, natural sound of the environment (background noise) as the detector can only respond to ultrasound frequencies. (b) Very high frequency ultrasound waves can penetrate greater depths of water. In hospital, ultrasound is used to obtain images of internal parts of the body. Ultrasound pulses are sent into the body by a transmitter placed in contact with the skin. Reflections or echoes are received from any surfaces within the body which has either a different density or a different structure or elasticity. The time delay of the echoes gives the depth within the body of the reflecting surfaces, and reflections in different directions can be used to build up an image of something inside Advantages of using ultrasound as compared to X-rays. (a) It is thought to be much safer than X-rays. (b) It can measure the depth of an object below the body surface, whereas an X-ray picture is flat with no indication of depth. (c) It can detect some differences between soft tissues in the body. In this way it is sometimes able to find tumours or lumps inside the body. Bibliography: nil Word Count: 237
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