I have a cooking thermometer that looks like a 10-15 cm long metal rod, that can be inserted into the thing you want to measure the temperature of:

Cooking thermometer

When inserted into boiling water, I observed that the reported temperature is invariably between 5 and 15°C lower when the tip is touching the container, than when I hold it a few millimeters above the bottom of the container without touching it (allowing a few seconds for the temperature readings to stabilize).

This is a bit surprising to me, as I expected it to (more or less) average temperature over the length of the metal rod ; the temperature of the container itself, while probably a little lower, should not have influenced the results this much.

How does such a thermometer work, and why does that happen?

  • 2
    $\begingroup$ Re, "I expected it to...average [the] temperature over the length of the...rod." If that's a meat thermometer, then that's not what the cook wants to know. The cook wants to know the temperature at the center of the steak/bird/burger/etc. The designers try to make it measure just the temperature of the tip. In the case of an electronic thermometer, that's a pretty easy goal to achieve: Electronic temperature sensors (e.g., thermocouples) can be very small. $\endgroup$ – Solomon Slow Mar 17 at 19:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.