Question #11, passage 2.
If an ultrasonic imager operates at a frequency of 157,000Hz, what is the SMALLEST object the image could detect?
A) 1mm
B) 1cm
c) 1m
d) no min size.
Answer: B.
I get we use v=w.l * frequency. rearrange for w.l=v/f and f = 157,000Hz then what? What's our velocity? it's not at all given. They put v as 1570m/s.. where the heck did that come from? The passage does say that v = 1570 m/s for FLESH, but this has nothing to do w/ the human body.. it can be an ultrasonic imager for anything?
If an ultrasonic imager operates at a frequency of 157,000Hz, what is the SMALLEST object the image could detect?
A) 1mm
B) 1cm
c) 1m
d) no min size.
Answer: B.
I get we use v=w.l * frequency. rearrange for w.l=v/f and f = 157,000Hz then what? What's our velocity? it's not at all given. They put v as 1570m/s.. where the heck did that come from? The passage does say that v = 1570 m/s for FLESH, but this has nothing to do w/ the human body.. it can be an ultrasonic imager for anything?
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