`ℏ = h/(2pi)`

1.05457182E-34

The constant `ℏ` is found using the following formula: `ℏ=h/(2π)`, where 

• h = Planck's constant (J*s)
• π = 3.14159265358979323846264338327950288

The symbol is read "h-bar."

`ℏ` is useful when frequency is measured in radians per second instead of cycles per second.   For this reason `ℏ` is also known as the reduced Planck constant or the Dirac Constant.

References

36.1 Classifying states by Benjamin Crowell, Light and Matter  licensed under the Creative Commons Attribution-ShareAlike license.