Temperature due to resistance calculator?

In summary, you might need to measure values at known temperatures and fit those to the Steinhart-Hart equation to get a more accurate temperature.
  • #1
ISX
120
0
Think this question is more of a physics than math question. Anyways I am trying to figure out how to make a calculator to figure out what temperature something is at based on the ohm reading I get. I have several readings to go by but I think doing it exponentially is the wrong way to go about it since the readings I calculate are not very accurate based on the quadratic regression method I have been doing.

Wikipedia shows the formula on this page (http://en.wikipedia.org/wiki/Callendar-Van_Dusen_equation) but I don't know how to figure out any of the coefficients or anything.

Thanks for any help I can get!
 
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  • #2
By:
ISX said:
... I am trying to figure out how to make a calculator to figure out what temperature something is at based on the ohm reading I get...
Do you mean using a thermistor, or just by plugging into any random piece of electronics?
The answer depends sensitively on your situation.
 
  • #3
Yeah just a little thermistor.

Guess it would be this equation then. http://en.wikipedia.org/wiki/Steinhart–Hart_equation

Temperature range of interest would be -40 to 212F. I just need help on the coefficient stuff.
 
  • #4
Unfortunately I think your best (if not only) bet is to measure some values at known temperatures and fit those to the equation. You have 3 constants, so you need at least 3 measurements, more would be better. The boiling and freezing points of water would be the easiest to do. If you don't have/want-to-use a thermometer, you could use the temperature of boiling and freezing of both pure and salt water for 4 total points.
 
  • #5
I do have many measurements. Here are a few. kOhms is first number Temp (F) is the second.

73.00 5.0
65.00 6.6
56.00 13.0
39.00 28.0
25.80 43.0
24.57 46.2
18.96 53.7
 
  • #6
I think you should use a thermistor because the temperature varies greatly with the heat-dissipation of the resistors.
 
  • #7
It is a thermistor..
 
  • #8
Hi ISX
ISX said:
I just need help on the coefficient stuff.
Do you have Excel or some other spreadsheet program? Just put the numbers you have for temperature and resistance and have the program do the curve fit to a polynomial for you.

For the values you provided, the chart is rather limited and I wouldn't suggest using it for values outside the tested limits, but attached is what you'd get. I'd suggest getting some more measurements, especially at the limits of your intended range (ie: test in boiling water, 212 F, and at -40 F).

Another alternative is to get an equation from the thermistor manufacturer.
 
Last edited:

1. What is a temperature due to resistance calculator?

A temperature due to resistance calculator is a tool used to calculate the change in temperature of an object due to its resistance to an electrical current. It takes into account the material's resistivity, length, and cross-sectional area to determine the temperature change.

2. How does a temperature due to resistance calculator work?

A temperature due to resistance calculator uses the formula T = (R * I^2 * p * L) / A, where T is the change in temperature, R is the resistance, I is the current, p is the resistivity, L is the length, and A is the cross-sectional area. By inputting these values, the calculator can determine the temperature change.

3. Why is it important to calculate temperature due to resistance?

Calculating temperature due to resistance is important because it helps predict the heating effects of an electrical current on a material. This information is useful in various industries, such as electronics and engineering, to ensure the safe and efficient use of materials.

4. What are the units of measurement used in a temperature due to resistance calculator?

The units of measurement used in a temperature due to resistance calculator may vary depending on the specific calculator, but typically include resistance in ohms, current in amperes, resistivity in ohm-meters, length in meters, and cross-sectional area in square meters.

5. Can a temperature due to resistance calculator be used for all materials?

No, a temperature due to resistance calculator is specific to materials with a known resistivity. It cannot be used for materials that do not follow Ohm's law, such as semiconductors or insulators.

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