The "reduced" Planck's constant:
The Planck's constant h is a fundamental physical quantity that relates the energy of a photon to its frequency:
E = h⋅f
The "reduced" Planck's constant ℏ (H-bar or Dirac's Constant) is another constant evaluated by simply dividing h by 2π. It is related to the formula for measuring angular frequency ( ω = 2πf ) measured in rad/s. Eliminating the extra 2π factors from momentum equations makes them cleaner & simpler. So the ℏ is used primarily for mathematical convenience and efficiency in quantum calculations.
