When should a bimetal stemmed or digital thermometer be calibrated?

• A. Only once when first purchased
• B. Only if the thermometer shows a reading above 100 °C
• C. Before each use and after being dropped
• D. After every cleaning with soap and water

Answer: (C)

Verified step by step guidance

1. Understand the purpose of calibration: Calibration ensures that the thermometer provides accurate temperature readings, which is crucial for reliable measurements.
2. Recognize that thermometers can lose accuracy over time or due to physical impacts, such as being dropped, which can affect their internal components.
3. Identify that calibration should be performed regularly to maintain accuracy, not just once or only under certain temperature conditions.
4. Note that cleaning alone does not affect the accuracy of the thermometer, so calibration is not required after cleaning unless other factors (like dropping) occur.
5. Conclude that the best practice is to calibrate a bimetal stemmed or digital thermometer before each use and after it has been dropped to ensure precise temperature readings.