At the boundary between two media if the IRC and ITC are added the result equals _____.

At the boundary between two media if the IRC and ITC are added the result equals _____.

• A. 100%
• B. 0%
• C. 50%
• D. 200%

Answer: (A)

Energy is conserved at a boundary between two media: the portion of the incident energy that is not reflected must be transmitted. The reflectance coefficient (IRC) and the transmittance coefficient (ITC) describe those portions, and together they account for all the incident energy. If there are no losses at the boundary, IRC plus ITC equals 1, i.e., 100%. That’s why 100% is the correct result. If there were absorption, the sum would be less than 100%. Options like 0%, 50%, or 200% would contradict energy conservation.

Energy is conserved at a boundary between two media: the portion of the incident energy that is not reflected must be transmitted. The reflectance coefficient (IRC) and the transmittance coefficient (ITC) describe those portions, and together they account for all the incident energy. If there are no losses at the boundary, IRC plus ITC equals 1, i.e., 100%. That’s why 100% is the correct result. If there were absorption, the sum would be less than 100%. Options like 0%, 50%, or 200% would contradict energy conservation.