Planck's law

The fundamental law of quantum theory that (a) has direct application in optical communications, i.e., lightwave communications, (b) describes the essential concept of the quantum of electromagnetic energy, i.e., describes the concept of the particle, granular, or corpuscular theory of electromagnetic radiation, particularly of light, and (c) states that the quantum of energy, E _ph , associated with an electromagnetic field is given by E _ph = hf where E _ph is the quantum of energy associated with a photon, h is a constant of proportionality, i.e., Planck's constant, and f is the frequency of the electromagnetic radiation, i.e., of the photon. Note 1: Planck's constant usually is given in joule · seconds and the frequency usually is given in hertz. Thus, the quantum of energy usually is given in joules. Note 2: The product of energy and time is sometimes referred to as the “quantum of action.” Hence, h is sometimes referred to as the “elementary quantum of action.” Synonym elementary...