Which of the following is a likely symptom when shielded capacitive sensors operate in dirty or damp conditions?

• A. No triggering occurs
• B. False triggers due to dirt or moisture on sensor face
• C. Sensor becomes immune to environmental changes
• D. Only metal targets are detected

Answer: (B)

The idea being tested is how surface contamination affects capacitive sensing. A shielded capacitive sensor detects changes in capacitance between its sensing face and nearby objects, but the shield mainly limits interference from surroundings; the sensing face still responds to what sits on or very close to it. When the face is dirty or damp, dirt or moisture forms a thin layer that changes the local dielectric environment or even creates a conductive path. That unintended change can resemble the effect of a target, causing the sensor to trip even though nothing real is there. So in dirty or damp conditions, false triggers due to dirt or moisture on the sensor face are the most likely symptom.

In contrast, sensors typically do not simply stop triggering (no triggering) just because of surface contamination; they tend to misbehave by producing extra triggers. Saying the sensor becomes immune to environmental changes is not accurate—contamination often makes the sensor more susceptible to surface conditions. And capacitive sensing isn’t limited to metallic targets; it responds to many dielectrics, though metal objects can produce stronger responses.