A plane monochromatic light wave of intensity Io falls normally on a plane-parallel plate both of whose

Question:

A plane monochromatic light wave of intensity Io falls normally on a plane-parallel plate both of whose surfaces has a reflection coefficient p. Taking into account multiple reflections, find the intensity of the transmitted light if
(a) The plate is perfectly transparent, i.e. the absorption is absent;
(b) The coefficient of linear absorption is equal to ×, and the plate thickness is d.