Conceptual question on wavelength&frequencies

[xregina12]

Here is a really simple conceptual question.

Explain why ultrasound can be used to prove the size and position of the fetus inside the mother's abdomen. Could audible sound with a frequency of 8000 s-1 be used for this purpose?

I know that audible sound has too low of a frequency (i.e not enough energy) for it to be used to probe the mother's stomach. However, can someone just further explain to me what this means conceptually? The audible sound just stops at the mother's stomach w/o being able to pass further to show what's inside?

I really appreciate any help.

 

[jbsteele]

Ultrasound uses sound waves of very high frequency (above 20,000 s-1) to create a detailed image of the fetus inside the mother's abdomen. This high frequency allows the sound waves to penetrate through the mother's tissue, creating a picture of the fetus on a monitor. Audible sound with a frequency of 8000 s-1 is too low for this purpose because it does not have sufficient energy to penetrate through the mother's tissue and create a picture. Instead, the sound would be blocked by the mother's tissue, making it impossible to measure the fetus' size and position.