Ultrasonic waves are sound waves greater than 20 kHz in frequency. In other words, they are propagating pressure oscillations, or alternating compressions and rarefactions, occurring at a periodicity of more than 20,000 times per second in a medium such as air or water. Bats produce and sense ultrasound waves in the 40 - 100 kHz frequency range.
Radio frequency electromagnetic waves are propagating oscillations of the electromagnetic field of frequency less than 300 GHz (300,000,000,000 times per second). They belong to the lower energy end of the same spectrum to which visible light belongs. Visible light consists of electromagnetic waves that oscillate in the 400 - 790 THz (400,000,000,000,000 - 790,000,000,000,000 times per second) frequency range. Electromagnetic waves do not require any medium such as air or water to propagate. Cheers, Santosh --- On Fri, 2/11/11, Charudatt Prabhudesai <[email protected]> wrote: > > Me: I want to know.But please do not post links. Write > in a nut shell,in broad lines of comparison and contrast. >
