What makes up the total electromagnetic radiation COMING FROM an object?

• A. A+R+T=1.0
• B. I+Q+V=1.0
• C. S+P+K=1.0
• D. E+R+T=1.0

Answer: (D)

The total electromagnetic radiation coming from an object is made up of three parts: what it emits due to its temperature, what it reflects from the surroundings, and what passes through if the material is not completely opaque. In infrared terms, that means emission, reflection, and transmission. These three components add together to give the total radiated energy you observe. The option that uses the letters for emitted, reflected, and transmitted energy correctly represents this sum, E + R + T. The other sets use symbols that don’t correspond to those three physical processes, so they don’t describe the total outgoing radiation. In many real cases an object is nearly opaque, so transmission is small, but emission and reflection are the dominant contributors.