A clinical thermometer serves a crucial role in healthcare settings, clinics, hospitals, and homes. Let’s delve into its functions and how it operates:

1. Measurement of Body Temperature:

   • The primary function of a clinical thermometer is to accurately measure a person’s body temperature. It provides essential information for monitoring health and diagnosing illnesses.
   • Fever, which is a common symptom of many medical conditions, can be detected using a clinical thermometer.

2. Working Principle:

   • A clinical thermometer operates based on the expansion of matter due to heat.
   • Here’s how it works:
     • The thermometer contains a bulb filled with a liquid (usually mercury or alcohol).
     • When the bulb is exposed to body heat, the liquid inside heats up and expands.
     • This expansion is proportional to the temperature.
     • The expanded liquid rises up a capillary tube, indicating the temperature reading.
     • Proper calibration ensures accurate temperature measurement.

3. Accuracy and Comparison:

   • Researchers have studied various thermometry techniques to determine their accuracy.
   • In one study, seven different commercially available thermometers were compared with a gold standard medical-grade thermometer.
   • The Braun tympanic thermometer (left ear) showed the best agreement with the gold standard, with a mean error of only 0.044°C.