Where inc is incident R=∣Jrefl∣∣Jinc∣R = \frac{|J_{\text{refl}}|}{|J_{\text{inc}}|}R=∣Jinc∣∣Jrefl∣ T=JtransJincT = \frac{J_{\text{trans}}}{J_{\text{inc}}}T=JincJtrans Note Jinc=Jrefl+Jtrans ⇒ 1=R+TJ_{\text{inc}} = J_{\text{refl}} + J_{\text{trans}} \;\Rightarrow\; 1 = R + TJinc=Jrefl+Jtrans⇒1=R+TVariational Method