Radiant flux Radiant flux In radiometry, radiant flux or radiant power is the radiant energy emitted, reflected, transmitted or received, per unit time, and spectral flux or spectral power is the radiant flux per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. The SI unit of radiant flux is the watt (W), that is the joule per second () in SI base units, while that of spectral flux in frequency is the watt per hertz () and that of spectral flux in wavelength is the watt per metre ()—commonly the watt
Per unit tax may lead to substitution to cheaper brands. Per unit tax A per unit tax, or specific tax, is a tax that is defined as a fixed amount for each unit of a good or service sold, such as cents per kilogram. It is thus proportional to the particular quantity of a product sold, regardless of its price. Excise taxes, for instance, fall into this tax category. By contrast, an ad valorem tax is a charge based on a fixed percentage of the product value. Per unit taxes have administrative advantages when it is easy to measure quantities of the product