[UK-CONTEST] Ultrasound beware!

[colin]

Hi Clive

Air has an acoustic impedance of near zero hence the need for coupling gel!

Soft tissue attenuates at about 0.3dB/cm/Mhz hence the need for low freqs 
for penetration through chunky Welshmen!

Bye the way that "operator" was probably a Radiologist by the sound of it!

cheers Colin GM0RLZ


----- Original Message ----- 
From: "Clive Whelan" <clive.whelan at btinternet.com>
To: "Chris Tran ZL1CT" <zl1ct1 at gm7v.com>
Cc: "UK Contest Reflector" <uk-contest at contesting.com>
Sent: Tuesday, March 24, 2009 10:59 AM
Subject: Re: [UK-CONTEST] Ultrasound beware!


> Thanks Chris
>
> I certainly didn't know that, and I have to say that I wouldn't have
> dreamt that air molecules could/would move that fast, atoms/electrons
> sure, but gignormous Oxygen and Nitrogen molecules amazing.
>
> Getting a long way OT for here, so better QRT now!
>
> 73
>
>
>
> Clive
>
>
> Chris Tran ZL1CT wrote:
>> Hi Clive
>>
>> No need to be concerned - these are not electromagnetic waves, but
>> sound (longitudinal) waves - they travel inside your body at about
>> 1500m/s - the higher frequencies giving better resolution.  They are
>> generally regarded as harmless, however there is some debate about
>> their possible harmful effect on foetus (foetii?)
>>
>> 73
>> Chris
>> ZL1CT/GM3WOJ
>>
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