What test would reveal hysteresis in a sensor's output?

• A. Compare readings while increasing and decreasing the input to look for lag and difference.
• B. Check battery level.
• C. Replace sensor without test.
• D. Increase sampling rate.

Answer: (A)

Hysteresis shows up when the sensor’s output depends on the history of the input, not just the current input value. To reveal this, you test by sweeping the input upward and then downward and watching for any lag or difference in the output at the same input level. If the upward path and the downward path produce different outputs for the same input, you’re seeing a hysteresis loop—the hallmark of memory in the sensor’s response.

Practically, you would slowly increase the input from a low value while recording the output, then decrease the input back down and record again. Compare the two curves or look for a gap between the paths at identical input points. Keep the test conditions stable (temperature, voltage supply) and allow the sensor enough time to respond, so you’re measuring intrinsic hysteresis rather than other dynamic effects. This approach directly tests the dependence on input history, which is exactly what hysteresis describes.

Other options don’t probe this behavior. Checking battery level doesn’t assess how output depends on past inputs. Replacing the sensor without testing skips diagnosing the behavior. Increasing the sampling rate might reveal fast noise or transients but doesn’t specifically demonstrate history-dependent output.