<p align="right">Last Update: <font color="#4f81bd">November 25, 2024</font></p>
## BIG IDEA
- A fundamental [[Physical constant|physical constant]] of foundational importance to [[Quantum mechanics|quantum mechanics]].
### Symbol
$h$
### Value
$6.63 \ x \ 10^{-34} \ \frac{J}{s} \tag{1}$
### Usage
- *Planck's constant*: More informal, historical emphasis.
- *Planck constant*: Formal, preferred in scientific and SI contexts.
- This usage aligns with how other constants are named, such as Boltzmann constant, Coulomb constant
### Reduced Planck constant
A fundamental physical constant used in quantum mechanics to represent the quantization of energy, angular momentum, and action.
### Definition of h-bar
$\hbar \ = \ \frac{h}{2 \pi} \tag{2}$
### Related Topics
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[[Home|Home]] | [[Quantum mechanics]] | [[Notes Vault/Physics Notes Vault/Quantity of Motion/Quantum Mechanics/Blackbody Radiation|Blackbody Radiation]] | [[Photoelectric Effect]] | [[Atomic Theory]]