For a negative temperature coefficient (NTC) sensor, how does resistance change with temperature?

• A. Increases as temperature increases.
• B. Remains constant.
• C. Decreases as temperature increases.
• D. Follows a nonlinear pattern not predictable.

Answer: (C)

NTC sensors have resistance that decreases as temperature increases. This negative temperature coefficient means the material’s ability to conduct improves with heat, so fewer ohms are needed to pass current at higher temps. The physics behind this is that rising temperature increases charge-carrier activity and reduces resistivity in the thermistor material, producing a lower resistance.

The relationship is nonlinear but predictable: resistance falls more quickly at lower temperatures and level-offs as temperature rises, and it can be modeled with standard equations (like the beta model or Steinhart-Hart) for calibration. So the idea that resistance rises with temperature or stays constant isn’t correct for an NTC device, and while the curve isn’t a straight line, it isn’t random or unpredictable.