What is a calibration curve and how would you generate one for a temperature sensor?

• A. A calibration curve maps sensor output to ambient humidity; generate by testing at different humidity.
• B. A calibration curve maps supply voltage to current; generate by varying voltage.
• C. A calibration curve maps time to drift; generate by aging test.
• D. A calibration curve maps true temperature to sensor output; generate by applying known temperatures across range, record outputs, then fit a curve.

Answer: (D)

Calibration curves show how a sensor’s reading relates to the actual quantity being measured. For a temperature sensor, you generate one by exposing the sensor to known temperatures across its usable range, using a reference thermometer or standard to know the exact temperatures. At each point, you record the sensor’s output (such as voltage, resistance, or digital value). Then you fit a curve to these data points that maps the true temperature to the sensor output. If the response is linear, a straight-line fit may be enough; if not, a higher-order polynomial or another model captures the nonlinearity. Once you have the curve, you can invert it to convert future outputs back into temperature readings. This process also helps account for systematic factors like electronics, wiring, and aging, and can be repeated to monitor drift over time. The other options describe different relationships that aren’t about linking true temperature to sensor output.