Thermal Resistance - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Thermal Resistance (/thread-8120.html) Thermal Resistance - KeithB - 04-05-2017 05:01 PM While playing with my Prime to answer the previous question, I found that dividing 10_W by 10_degC gives an error. In high power electronics this is a very common proportionality equivalent to resistance. typically measured in degC/W (though K/W is also used, and probably more correct) Knowing this proportionality you can calculate the increase of temperature of a device given the power dissipation. Can we see about adding this to the units calculations? How about a way to add "proportionalities" as some form of user units? RE: Thermal Resistance - KeithB - 04-05-2017 06:39 PM In this case it is required to use K, so as long as I do that, everything is fine. It still might be nice to have user defined units along the line of: ohm = V/A RE: Thermal Resistance - mark4flies - 04-09-2017 01:54 PM I was able to enter this ratio as [numerator] / [denominator] > Shift Units Power W / Shift Units Temperature degC Enter. This approach is consistent with the way units generally work, but it does seem a bit awkward or round-about. If I try to divide the two individual unit objects like you, then I see the same error.