chapter 9 sound and ultrasound

Question 1

human frequency range

Answer 1

20Hz to 20000Hz

Question 2

what are sound waves?

Answer 2

vibrations (Longitudinal waves) that travel through a medium, and cannot travel through a vacuum

Question 3

echoes

Answer 3

caused by sound waves reflected from a smooth, hard surface

Question 4

increasing the frequency of the sound…

Answer 4

increases its pitch

Question 5

increasing the amplitude of the waves…

Answer 5

increases the loudness

Question 6

ultrasound waves

Answer 6

waves above 20000Hx

Question 7

how are ultrasound wave used in medicine?

Answer 7

ultrasound scanning and destroying kidney stones

Question 8

how do ultrasound scanners work?

Answer 8

an ultrasound scanner consists of an electronic device called a transducer. The transducer produces and detects pulses of ultrasound waves.
Each pulse from the transducer:
-is partially reflected from the different tissue boundaries in its path
-Returns to the transducer as a sequence of reflected pulses from the boundaries, arriving back at different times. The pulses are then detected by the transducer, they are used to build up an image on the screen.

Question 9

advantages of using ultrasound instead of X-ray

Answer 9

-non-ionising–> harmless when used for scanning
-reflected at boundaries between different types of tissues so they can be used to scan organs and other soft tissues in the body