luminous efficacy


the quotient of the luminous flux of a radiation and its corresponding radiant fluxSymbol: K
the quotient of the luminous flux emitted by a source of radiation and the power it consumes. It is measured in lumens per wattSymbol: η v, Φ v



Punctuation marks help make writing easy to read and understand. Some of the most important ones are the period (.), comma (,), question mark (?), and exclamation point (!). How well do you know how to use them? Find out in this quiz!
Question 1 of 10
Which punctuation mark is best for this sentence? "Can I watch a movie __"
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012