Electromagnetic radiation and B fields in EMR are in-phase (see math section below). An important aspect of light's nature is its frequency. The frequency of a wave is its rate of oscillation and is measured in hertz, the SI unit of frequency, where one hertz is equal to one oscillation per second. Light usually has multiple frequencies that sum to form the resultant wave. Different frequencies undergo different angles of refraction, a phenomenon known as dispersion. A wave consists of successive troughs and crests, and the distance between two adjacent crests or troughs is called the wavelength. Waves of the electromagnetic spectrum
Live! Go for What You Know of Travers and Thrall bridged the gap between what it calls "dramatic changes" in metal in the late 1970s: Travers emblematized "the blues-rock sound of sixties and seventies metal" whereas Thrall's playing represents the newer wave in metal (represented by Eddie van Halen): "The combining of the two players' solos during this time showed a rare detente between two generations of hard rockers and, although short-lived, it was extremely exciting." The album was produced by Tom Allom, who had worked on the first five Black Sabbath albums as a sound engineer, had produced two albums by The Tourists, and would