TBR, Sound, Passage 3, pg 26 # 16

[Sammy1024]

16. Bats use active sonar to detect small insects. How does the bat's signal compare to the submarine's sonar?

A. Bat sonar must have a shorter wavelength.

Because the target for the bat is considerably smaller than for a submarine, the wavelength must be shorter for the bat's radar signal than the submarine's sonar signal. The wavelength of the signal must be roughly equal in size to or shorter than the object....

I understand the frequency part, which is the second part of the explanation, but I was wondering is it a fact that for smaller objects you use a shorter wavelength? Is it something from the books?

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[DrknoSDN]

A long wavelength would wrap around a small target instead of reflecting off it.
If your purpose was to get the sound to go around objects then longer wavelength would be ideal but that't not the purpose of sonar.

 

[Sammy1024]

Is this like one of those random facts or was it in a prep book? I hadn't read about this fact before.

 

[DrknoSDN]

No clue about that. I don't recall reading about it at all for the MCAT. Maybe it's not on AAMC subject list? I think if they are going to talk about wavelength and waves bending it would be using light waves (single slit diffraction experiment) instead of sound waves. Not exactly the same thing but it's close.

More information here (with pictures that directly relate to your question.) =D
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/diffrac.html

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[Sammy1024]

Thank you so much! Ugh please take my MCAT for me. Haha jk.