Heating & Cooling a Thermometer

• Thermometer is cooled, the molecules move more slowly, get closer together (liquid contracts) & move down in the tube.
• Thermometer is heated, the molecules move faster, get slightly further apart (liquid expands) & move up in the tube.
• Liquid inside (ethyl alcohol & red dye) or (mercury in past) heated up... - more thermal energy... The liquid expanded & moved "up" the enclosed tube.
• A temperature scale (°C or °F or K) on the thermometer would measure the expansion of the liquid & determine the temperature. A temp. scale has gradients (ticks on the side) that show temp. changes.
  
  
  
  Thermometers demo (download .swf, run in Ruffle)