Lower emissivity increases potential error due to reflected background radiation.

• A. They do not affect measurement
• B. They increase measurement sensitivity
• C. They require calibration
• D. They increase reflected background influence

Answer: (D)

Emissivity governs how much energy a surface emits versus how much it reflects. In infrared measurements, the detector sees both the object's own emission and background radiation reflected from the surroundings. When emissivity is low, a larger portion of the signal comes from reflected background rather than the object's emission, so the measured temperature is more influenced by the background and more prone to error. That’s why the statement is correct: lower emissivity increases the potential influence of reflected background radiation. High emissivity reduces this effect because most detected energy comes from the object's own emission. Calibration can help compensate for emissivity effects, but the issue described is the increased reflected background contribution.