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.
Back to Top. A Light meter is a device which is used for the measurement of amount of light. One of the most important uses of light meter is in Photography.In Photography, it is used to find proper exposure of light.