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The circular beam has incident power p super I is incident from the medium 1 to the interface area A of medium 1 and 2. The incident beam gets reflected within the medium 1 with a reflected power, P sup r. The power p sup t transmitted from the medium 1 to 2 through the surface A. The incident power, p sup I, A cosine of theta sub I, incident with an angle theta sub I. The reflected power, A cosine of theta sub r reflected with an angle theta sub r. The transmitted power, p sup t, A cosine of theta sub t transmitted with an angle theta sub I in the medium 2.