Ultrasound

[Serj]

I need to buy polarised transducers capable of emitting sound at 25kHz. Which one of these should I buy?
http://www.imagesco.com/catalog/sensors/film.html
http://www.imagesco.com/catalog/sensors/piezo.html

[berkeman]

I need to buy polarised transducers capable of emitting sound at 25kHz. Which one of these should I buy?
http://www.imagesco.com/catalog/sensors/film.html
http://www.imagesco.com/catalog/sensors/piezo.html
It's a trick question. There's no such thing as polarized ultrasound. Sound waves are longitudinal, not transverse. :tongue2:

[Astronuc]

There's no such thing as polarized ultrasound. Sound waves are longitudinal, not transverse. Ah, not so! While is virtually impossible to generate shear waves in gases, shear waves are possible in liquids and solids, or basically any elastic material.

Sound can be induced as shear waves in addition to longitudinal waves. And there are hybrid waves (Lamb waves). All these are well known in the application of ultrasonics in non-destructive testing and imaging.

For example -
Ultrasonic methods for characterizing polymeric material
http://pubs.acs.org/hotartcl/ci/00/feb/alig.html

Generation of Horizontally Polarized Shear Waves with EMAT Transducers
http://www.ndt.net/article/0398/huebsch/hueb.htm

I'll see if I can answer the OP later.

[berkeman]

No kidding? I never knew that. Thanks, Astro, I learn something new every day, especially here on PF.:biggrin: