1. Why Touch Cannot Be Trusted
Dip your left hand in warm water and your right hand in cold water for a minute, then plunge both into lukewarm water. Your left hand says it is cold; your right hand says it is hot! Our senses provide relative sensations, not standardized metrics.
Temperature is the objective numerical measure of the degree of hotness of a body, measured on the Celsius scale ($^\circ\text{C}$) using a thermometer.
2. Clinical vs. Laboratory Thermometer
| Feature | Clinical Thermometer | Laboratory Thermometer |
|---|---|---|
| Measurement Range | $35^\circ\text{C}$ to $42^\circ\text{C}$ (human body range) | $-10^\circ\text{C}$ to $110^\circ\text{C}$ (wide laboratory range) |
| Presence of Kink (Constriction) | Present: A small kink near the bulb prevents mercury from falling back before reading. | Absent: Must be read while submerged in the liquid; mercury drops immediately on removal. |
| Primary Use | Measuring human body temperature (normal: $37.0^\circ\text{C}$). | Measuring boiling points, reaction temperatures in beakers. |