Mercury Thermometer

A thermometer is an instrument used to measure temperature. Its operation is based on the thermal expansion of certain substances. A common type of thermometer is the liquid thermometer, which measures temperature by the expansion of a liquid in a thin glass tube, known as a capillary tube. The glass reservoir typically contains mercury, a substance highly sensitive to temperature changes. The volume of mercury (or another measuring liquid) varies with temperature due to thermal expansion, where the change in size is proportional to the amount of heat supplied. This type of thermometer is known as a dilational thermometer, as it relies on the expansion of the liquid, which is nearly uniform. Mercury is often used for high-temperature measurements, with a typical range from -39 to 357 °C, which corresponds to its melting and boiling points. In laboratories, mercury thermometers generally measure temperatures within the range of -30 °C to 300 °C. The model demonstrates various temperatures and the behavior of fluid particles within the thermometer. As the thermometer absorbs heat, the internal energy of the fluid increases, causing the particles to move faster, which is reflected by a rise in temperature. When heat is removed, the internal energy decreases, and particle movement slows, resulting in a lower temperature reading. The thermometer’s scale is calibrated in degrees Celsius (°C).