A sensor converts a physical quantity into an observable signal. A temperature sensor might produce a voltage or resistance change that a measuring system converts into a temperature estimate. A useful model separates sensitivity, offset, noise, calibration and dynamic response: a large output change does not guarantee accuracy if the calibration drifts. Sensors also load the system they measure, for example by drawing heat or electrical current. The complete measurement chain includes the sensor, readout electronics and the model mapping the signal back to the intended quantity.
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