Answer Show Verified Hint: The question given to us required the knowledge of different types of waves and also which kind of waves can travel in vacuum. Here, we will discuss mechanical waves and electromagnetic waves and their medium of propagation and also find which of the above waves is mechanical waves. Complete step-by-step solution: Note: From the above discussion we got to know that seismic waves require a medium for propagation that means cannot travel in vacuum. The other examples of the mechanical waves that cannot travel in vacuum are infrasonic waves, sound waves, vibrations, wind waves etc.
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Why do ultrasound waves not travel through air well?
I'm at an internship and I saw a container labeled ultrasonic gel, which is used to prevent air from coming between a scanner and the human body. This is necessary because apparently ultrasound doesn't travel through air well. Why is this? (don't say because the density is low, because I will reply by asking why low density means ultrasound waves can't travel far) Also, I'm
not sure if it's that the waves spread out in air, or just that they don't propagate as far in air. The website were fairly obscure since they were targeting their customers, not curious high schoolers who want to learn physics.. Answers and Replies
This is necessary because apparently ultrasound doesn't travel through air well. Why is this? (don't say because the density is low, because I will reply by asking why low density means ultrasound waves can't travel far) because the lower the density the higher the attenuation EDIT: to expand on that ...
consider why sound doesn't travel through a vacuum ... same thing To quote a movie line ... Dave
consider why sound doesn't travel through a vacuum ... same thing To quote a movie line ... Dave more questions that came
up during research: ps nice quote from alien
he said that when the waves hit a boundary, the majority of it is reflected since air/skin is a pretty high density change. and then if you further on try to scan for bones and blood with this significantly weaker wave, the return signal will be barely visible. (is this called boundary attenuation?) may well be, I am not sure
yes that and the fact that in a lower density, there are less particles(molecules) of the medium with which the sound wave cam be propagated other forms of energy --- really only one other form = heat
No, sound is a propagating mechanical wave, light is a propagating electromagnetic wave ... very different beasts They are produced by different mechanisms and as such their propagation is different light will travel through a vacuum, sound never will regardless of its frequency cheers
I went and read a bit on attenuation and also talked to the main researcher at the company (dads friend who knew me as a child so i could approach him), He gave an explanation that was slightly different (because he was addressing ultrasound in ultrasonic machines specifically), he
said that when the waves hit a boundary, the majority of it is reflected since air/skin is a pretty high density change. and then if you further on try to scan for bones and blood with this significantly weaker wave, the return signal will be barely visible. (is this called boundary attenuation?) There are ultrasound transducers designed to match the impedance of air and they can sent significant ultrasound power into the air.
The main reason for using coupling gel is the one given by the researcher in the lab. There are ultrasound transducers designed to
match the impedance of air and they can sent significant ultrasound power into the air.
to revive a not too old thread The main reason for using coupling gel is the one given by the researcher in the lab. In fact it has a HUGE effect ... the gel is used specifically to remove air pockets / bubbles between the transducer and the skin Dave
Yeah, it's a huge effect. But is due to impedance miss-match and not to attenuation. You should not quote out of context. In the following paragraph I mentioned how significant may be the effect of reflection at the interface air-transducer.
Yeah, it's a huge effect. But is due to impedance miss-match and not to attenuation. You should not quote out of context. In the following paragraph I mentioned how significant may be the effect of reflection at the interface air-transducer.
Rubin, to try to simplify it and to put an image to it, imagine you are at a concert and it's crowded. Now another concert where you have been, was way more crowded where you almost stepped on your next fellow's foot. At that first concert someone tripped and fell onto someone, but nobody was behind that someone so only that someone fell as well. At the second concert, someone
tripped and fell on two persons, and those two persons fell on someone else too. It doesn't make it an infinite wave of people falling it just increases the depths of the wave by a LOT (The higher the density, the more crowded the concert is, and the fact that it's liquid as well has to play a big role in it).
Given all of this, is it safe to assume that the gel is engineered to have the same impedance as the body, as a means of illuminating the boundary between the two? And if so, is it made to match the impedance of the skin, or of the tissue underneath (or are they the same)? This all sounds a lot like the semi-elliptical can full of salt water used in lithotripsy.
Cool link! My son and I are not making ublec this weekend, I guess.
This is in the same ballpark as the reason why our ears have all that complicated arrangement of small bones (ossicles) which act as levers and Transform the (low) impedance of sound in air to the (high) impedance of sound in the watery environment of the inner ear. Suggested for: Why do ultrasound waves not travel through air well?
Why ultrasonic waves Cannot travel in vacuum?Sound energy transfer in the form of vibrations, these vibrations need matter to travel, absence of matter in a vacuum makes these waves impossible to travel.
Can ultrasonic waves travel in vacuum?Sound waves cannot travel in vacuum.
Why does ultrasound not travel through air?Therefore, we can conclude that the attenuation is maximum in terms of air medium. Thus, an ultrasonic wave which is traveling at an enormous frequency will dissipate proportionally in the air medium therefore, it does not travel through the air.
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