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I have an infrared thermometer that supposedly goes up to 1200F (https://www.amazon.com/gp/product/B00IT0ODPQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1).

However, I used this on my electric stove when turned to max. The coils are cherry red which is normally 1500F. Nichrome is usually rated to go up to 1400F.

Nevertheless, the thermometer never showed more than 900F.

What is the problem? Are these types of thermometers just unreliable?

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    $\begingroup$ What independent evidence do you have that the surface of the coils was anything other than 900F? Sorry, but "cherry red which is normally 1500F" is not exactly a calibrated reference. $\endgroup$ – Dave Tweed Nov 20 '16 at 16:41
  • $\begingroup$ @DaveTweed When metal or ceramic is glowing red it is necessarily over 1300F. Has something to do with physics. I am not a physicist so I don't know the details, however, what I do know is that something that is glowing cherry red has to be way hotter than 900F. $\endgroup$ – Wallace Park Nov 20 '16 at 17:31
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Infrared meters are reliable. They are, however, indirect measurements. For you to measure temperature you need to know the emissivity of your material, and any intervening material, in the temperature range your measuring. This info must be input to the device for it to show correct values.

Here is a good reference for starting out. Measuring stuff is rarely just pointing a sensor at your problem and reading output values.

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