How a Thermometer Works - Science Explanation & Diagram #2253438 (License: Personal Use)

The left panel shows heat energy entering the red bulb of a liquid-in-glass thermometer from the surrounding medium, while the right panel demonstrates how that absorbed heat causes the red liquid to expand and rise up the narrow glass tube. This visual explains the fundamental principle of thermal expansion used in traditional thermometers.

Used in educational web pages, science blogs, or K-12 curriculum materials to explain temperature measurement principles; matches user intent for understanding basic physics concepts visually.