Sound is transmitted through a medium by inducing vibrational motion of the molecules forming part of it. Human hearing threshold is reached when the frequency of sound is higher than 16-18 kHz. Ultrasound comprises the region of frequencies between 18 kHz and 100 MHz, the upper limit not being sharply defined (Figure 1). This broad region can still be divided into two different regions: power ultrasound between 20 and 100 kHz and diagnostic ultrasound between 1 and 10 MHz. The above classification relies on the capability of energy transmission into the medium at the lower frequencies, which induces the cavitation phenomenon.

Relevant applications of ultrasonic energy include its use in animal communications (e.g. bat navigation and dog whistles), medicine for fetal imaging, underwater range finding (SONAR) and nondestructive testing for metal flaws. Recently, ultrasound has also been considered a potential source for enhancement of chemical reactivity. A large variety of chemical and industrial processes rely on high intensity ultrasonica-

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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