Cycle per second Cycle per second The cycle per second was a once-common English name for the unit of frequency now known as the hertz (Hz). The plural form was typically used, often written cycles per second, cycles/second, c.p.s., c/s, ~, or, ambiguously, just cycles. The term comes from the fact that sound waves have a frequency measurable in their number of oscillations, or "cycles", per second. With the organization of the International System of Units in 1960, the cycle per second was officially replaced by the hertz, or reciprocal second, "s" or "1/s". Symbolically, "cycle per second" units are "cycle/second", while hertz
Stilb (unit) Stilb (unit) The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 10 nits (candelas per square meter). The name was coined by the French physicist André Blondel around 1920. It comes from the Greek word "stilbein" meaning "to glitter". It was in common use in Europe up to World War I. In North America self-explanatory terms such as candle per square inch and candle per square meter were more common. The unit has since largely been replaced by the SI unit: candela per square