They Swing

Cont'd from "Left Side, Right Side, Bounded And Kinky" dated 10 Aug 2015,

For the case of $\mu_2\gt\mu_1$,

$\alpha_{2s}\lt\alpha+\Delta\theta$

and

$\alpha_{2p}\gt\alpha-\Delta\theta$

It is possible that $\alpha_{2s}$ crosses below $\alpha_{2p}$ when $\Delta\theta\lt0$.  $\alpha_{2s}$ is not necessarily the left beam.  $\Delta\theta$ can be adjusted to swing the beams over $\alpha$.