Which thermometer type can measure ambient temp, surface temp, and internal temp?

• A. Infrared/laser
• B. Bi-metallic
• C. Thermocouple
• D. Digital Bi-metallic

Answer: (C)

Measuring temperature in air, on a surface, and inside a material relies on a sensor that can be used in different ways. A thermocouple achieves this because it uses a junction of two dissimilar metals that generates a small voltage proportional to the temperature at the junction. With the right probe, you can expose the junction to ambient air to read the surrounding temperature, press the probe against a surface to read surface temperature, or insert the probe into a material, liquid, or tissue to read internal temperature. This versatility makes it capable of measuring all three contexts. Infrared devices read only surface temperatures and can be affected by emissivity; bi-metallic variants mainly measure ambient air temperature and have slower response and limited internal-read capabilities.