Reduced Planck Constant

Planck's constant divided by 2π — the natural unit of angular momentum and the scale of quantum effects.

Specifications & Metrics

symbol

ħ

status

Exact — derived from defining constants

value

1.054571817 × 10⁻³⁴ J·s

Relative Scale in Constants

Core Principles & Analysis

• Equals h/2π, absorbing the 2π that appears whenever frequencies become angular frequencies.
• Sets the floor of Heisenberg's uncertainty principle, Δx·Δp ≥ ħ/2.
• Particle spin is quantized in units of ħ/2 — fermions carry half-integer, bosons integer multiples.

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