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gcse science P4 - D

specific for ocr gateway additonal science B.

QuestionAnswer
what is frequency in sound waves? what is frequency linked to? -number of waves produced each second -pitch
what is amplitude in sound waves linked to? loudness
what is compressions in sound waves? area where particles are close together
what is ultrasound produced by? vibrating particles that form a longitudinal wave
what are the features of a longitudinal wave? -they can't travel through a vacuum. the denser the medium, the faster a wave travels -the higher the frequency or pitch, the smaller the wavelength -the louder the sound/the more powerful the ultrasound, the larger the amplitude
what is ultrasound? a sound of a higher frequency that humans can't hear
what does ultrasound travel as? a pressure wave - compressions and rarefactions
what are the vibrations of particles like in a longitudinal wave? they are in the same direction as the wave
what are the vibrations of particles like in a transverse wave? they are at right angles to the direction of the wave
what are the main 2 uses of ultrasound? -to break down kidney stones -in a body scan
how does ultrasound work in the process of breaking down kidney stones? -high powered ultrasound beam is directed at kidney stones -ultrasound energy breaks the stones into smaller pieces -tiny pieces are then excreted from the body in a normal way
how does ultrasound work in the process of a body scan? -pulse of ultrasound is sent to the body -at each boundary between different tissues, some ultrasound is reflected and the rest is transmitted -the returning echoes are recorded and used to build up an image
why can ultrasound be used for body scans?1 reflections from boundaries of organs create echoes which build up the image
what happens if the tissues are very different, e.g. blood and bone? most of the ultrasound is reflected, leaving very little to penetrate further into the body
why is ultrasound preferred to x-rays? -differentiates between soft tissues better -doesn't damage living cells
Created by: jirwin
 

 



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