Planck's constant

A physical constant that (a) is equal to 6.626 × 10⁻³⁴ J · s (joule · seconds) and (b) usually is designated by h. Note 1: Planck's constant is used in many relations that apply to electronic and fiber optic systems, including automatic data processing, computer, communications, information, control, sensing, telemetry, endoscopic, illumination, and imaging systems. See also automatic data processing system, communications system, computer system, constant, control system, electronic, endoscopy, fiber optic system, illumination, imaging, information system, joule, physical, second, sensing, telemetry. Note 2: Applications of Planck's constant include:

• Photon energy is given by the relation E _ph = hf where h is Planck's constant and fis the frequency of the radiation associated with the photon. The energy content of a photon of one-micron (1-μm) wavelength is about 1.2 ev (electron · volts). Electrons in chemical elements and compounds can only exist in certain energy levels....