A restricted class of OTC drugs also exists in the U.S. This restricted class includes drugs such as pseudoephedrine, emergency contraception, and some Schedule V controlled substances. These products, while considered OTC, are kept behind the pharmacy counter and must be dispensed by a pharmacist pursuant to proper identification, age verification, and patient education.
The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.
The diameter of a light bulb is measured in two ways, in metric it is the number of millimeters and in imperial measure if the the number of 1/8 inch increments.hese are just a few of the ways of measuring light bulbs and the light they produce. The physical dimensions of an LED light bulb include: These are the discussed in more detail in the specific subjects in EagleLight's LED University.