The power in a light beam is proportional to the squareof its electric field, and the electric field for a beam travelingin an attenuating medium can be given by Equation E =Eoe-αzsin(ωt - kz). The attenuation coefficient in that equation determines the loss. On the other hand, we frequntly discuss the loss in terms ofdecibels per kilometer. => Show that the power change in dB/kmand the attenuation coefficient α are related by γ =-8.685α, where α is given in the unitskm-1.