Classically allowed region
= Classically allowed region
{title2=$E>V(x)$}
For a particle of fixed <energy> $E$, a <classically allowed region> has positive classical <kinetic energy> $E-V(x)$. For a constant <potential energy>, the stationary <wavefunction> is a combination of $e^{ikx}$ and $e^{-ikx}$, where $k=\sqrt{2m(E-V)}/\hbar$ is the <wavenumber>. In a varying <potential energy> this local value underlies the <WKB approximation> away from turning points.