How can we produce ultrasound?

[ragav]

Hey everybody,

I have some simple questions on ultrasound and its production...

How can we produce ultrasound? (or rather "where can I get detailed information on the methods of producing ultrasound?")

What are the general properties of ultrasound?

Regards.
--
rAgAv

 

[Danger]

Ultrasound is the same as any other sound. The 'ultra' prefix indicates that it's above the frequency range audible to humans. As with light, the energy becomes denser as the frequency increases, so something like the welding of plastic or suchlike becomes possible with very short wavelengths.
It can be produced quite easily with such low-tech methods as dog whistles or tuning forks. Most often now, however, piezoelectric transducers are used. They're simply solid-state 'speakers' the same as you'd find in a talking birthday card or a smoke alarm. Quartz crystals, for instance, are capable of extremely high vibration rates and thus high frequency sound production.