Ch 1.2 The fundamental constant $h = 6.626 \times 10^{-34}$ J$\cdot$s setting the scale of quantum effects. The reduced Planck constant $\hbar = h/(2\pi) = 1.055 \times 10^{-34}$ J$\cdot$s appears throughout quantum mechanics. When $\hbar \to 0$, quantum mechanics reduces to classical mechanics. *Se