The Planck Constant (h) is 6.626068 × 10-34 m2 kg/s. The relation of a Photon's energy to frequency is ```E = h × f ``` (E being energy, f being Frequency). The Reduced Planck Constant (or Dirac Constant, abbreviated ℏ) is h/2π, which is convenient because many equations incorporate this expression. A set of units based upon fundamental constants, including the Planck constant determine some minimal scales regarding current physical laws: Planck Length, Planck Mass, and Planck Time. For example, a black hole of the Planck mass (a Planck Hole) is considered as small as they can be. ```tP ≡ √(ℏG/c5) mP ≡ √(ℏc/G) lP ≡ √(ℏG/c3) ``` tP - Planck time (5.39 × 10-44 s). mP - Planck mass (2.18 × 10-5 g). lP - Planck length (1.62 × 10-33 cm). G - Gravitational Constant. c - speed of light. (physics,constant,quantum mechanics) http://en.wikipedia.org/wiki/Planck_constanthttp://en.wikipedia.org/wiki/Planck_units Referenced by: Black-Body Radiation Bohr Model Carbon Monoxide (CO) Frequency Planck Function Saha Equation Stefan-Boltzmann Constant (σ)