Photons may occur in the form of x-rays, gamma rays, or quanta of light. The energy (E) of a photon is expressed as the product of its frequency (v) and Planck's constant (h), as in the equation E = hv. X-ray photons occur in frequencies of 10 18 to 10 21 Hz and energies that range upward from 1 KeV.
Confidence votes 52.5K. In the US, the standards called General Industry Standards are the OSHA standards at 29 CFR 1910 and are sometimes called Part 1910.
The Standard Industrial Classification SIC is a system for classifying industries by a four-digit code. Established in the United States in 1937, it is used by government agencies to classify industry areas.