Q: What is Ultrasound?
A: Ultrasound is the process of using sound to create an image of something internal that cannot typically be seen with the human eyes. Other common applications include cleaning, disinfecting/disintegration, humidifying, welding, sonochemistry, sonic weapons and wireless communication.
It is defined as sound frequencies greater than 20 kHz and in air the (at normal atmospheric pressure) the wavelengths are 1.9 cm or less. High-power applications of ultrasound often use frequencies between 20 kHz and a few hundred kHz and it has the ability to create rather intense effects. Above 10 watts per square centimeter, cavitation can be inducted in liquid media, and some applications might even use up to 1000 watts per square centimeter in order to induce chemical changes or produce significant effects by direct mechanical action, such as inactivating harmful microorganisms.