Nonelectrical thermometers
- Liquid-in-glass: mercury or alcohol volume \(\propto\)T, read as change in height of liquid.
- Bimetallic strip: 2 metals with different thermal expansion coefficients fused together. Increasing temperature \(\to\) strip bends more \(\to\) drives an arrow across a dial.
Contact electrical thermometers
- Thermistors: resistors where the resistance varies with temperature. Known voltage established \(\to\) current measured \(\to\) temperature of resistor calculated
- Thermocouples: 2 conductors in electrical contact. A temperature difference will create a voltage by the Seebeck effect.
Noncontact electrical thermometers
- Infrared thermometers: measure the intensity and wavelength of emitted IR blackbody radiation. Can only measure surface, not core temperature.