To know how ultra sound works and how it compares to x-rays. 26/04/2017 Physics 3 Ultrasound To know how ultra sound works and how it compares to x-rays.

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How sound travels… 26/04/2017 As we know, sound waves are formed when something vibrates. But how does the sound reach our ears? Air molecules 2) The vibrations pass through air by making air molecules vibrate 3) These vibrations are picked up by the ear 1) An object makes a sound by vibrating

Sound can be reflected and refracted 26/04/2017 An Echo is a reflected sound wave Echolocation is also used in the shipping industry but remember Sound in air = 330m/s Sound in water = 1500m/s Bats use echoes to locate insects. They time how long the echo takes to come back and use that to locate the insect

Using an oscilloscope 1) Quiet sound, low frequency: 26/04/2017 1) Quiet sound, low frequency: 2) Quiet sound, high frequency: 3) Loud sound, low frequency: 4) Loud sound, high frequency:

Ultrasound 26/04/2017 Ultrasound is the region of sound above 20,000Hz – it can’t be heard by humans. There are a number of uses for ultrasound: Pre-natal scanning Cleaning – it can be used to dislodge dirt Detecting flaws or cracks Medical treatment

How does ultrasound work? 26/04/2017 Ultrasonic waves are partly _________ at the boundary as they pass from one _______ to another. The time taken for these reflections can be used to measure the _______ of the reflecting surface and this information is used to build up a __________ of the object. Words – depth, reflected, picture, medium

Kerboodle Animation 26/04/2017 millepau 1513967 3136663

Speed Calculation 26/04/2017 Distance travelled = speed of ultra by pulse sound waves in X transit time body tissue s (m) = v (m/s) x t (s) However, the depth of the boundary is only half of the distance travelled: Distance to boundary = speed of ultrasound waves X transit time

Calculating the speed of sound 26/04/2017 We can work out how far away surfaces are using ultrasound by connecting the transducer to an oscilloscope and measuring the transit time of each pulse. This is the time taken by the pulse to travel from the transmitter to and from the boundary that reflected it.

Using an oscilloscope with ultrasound 26/04/2017 Consider a block of metal with a flaw: 20ms/div Q. If the speed of the ultrasonic wave is 3,000m/s how far away is the flaw from the detector?

X-Rays Vs Ultrasound 26/04/2017 Evaluate the advantages and disadvantages of using ultrasound and x-rays (4 marks) Ultrasound Non-ionising, harmless when scanning Reflected at boundaries between different tissue types so they can be used to scan different organs and soft tissues. X-Rays Highlight deformities/breaks in bones, can be used in cancer treatment

Opinions on investment in pre natel scans: Kerboodle 26/04/2017 Opinions on investment in pre natel scans: Kerboodle