Thermistor Problem: Finding Material and Equation

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In summary, the conversation discusses the use of a thermistor and its properties. The equation ΔR=kΔT is mentioned, and the need to find the temperature coefficient of resistivity and match it to a material is mentioned. The speaker also mentions the non-linearity of thermistors and the need for measuring its characteristics. They suggest using Ohm's law and plotting the results to determine the slope, or k, of the curve.
  • #1
brendanrundle
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Ok so I am trying to figure out what type of material a thermistor should be, and am using the equation ΔR=kΔT (R being the resistivity, k being the temperature coefficient of resistivity, with which I want to find and match it up with a material, and T being the temperature). I have the change in temperature and the resistivity is initially at zero, but I don't have either the final resistivity or k. Can anyone give me some guidance? Thanks!
 
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  • #2
Thermistors are often non-linear. Some are designed as self heating regulation devices, others as temperature sensors. You need to measure the characteristics of your device and identify thermal conductivity regarding self heating.
Start here; http://en.wikipedia.org/wiki/Thermistor
 
  • #3
Is this a school experiment? It sounds like one I supervised a few years ago.

If so, you need to measure the resistance at several temperatures (known temperatures - ice water, boiling water, etc) using Ohm's law with measured voltages and currents. Then plot your results.

k is the slope of the curve.
 

1. What is a thermistor?

A thermistor is a type of temperature sensor that uses the principle of electrical resistance to measure changes in temperature. It is made of a semiconductor material that has a resistance that varies with temperature.

2. How does a thermistor work?

A thermistor works by changing its electrical resistance in response to changes in temperature. As the temperature increases, the resistance of the thermistor decreases, and vice versa. This change in resistance can be measured and used to calculate the temperature.

3. What kind of material is used to make a thermistor?

Thermistors are typically made of ceramic materials such as metal oxides, such as manganese, cobalt, nickel, or iron. These materials are chosen for their high temperature coefficients of resistance, which means their resistance changes significantly with small changes in temperature.

4. How do you find the equation for a thermistor?

The equation for a thermistor is typically found by conducting experiments and collecting data on the temperature and corresponding resistance values. This data is then used to create a graph, and the equation can be derived from the slope of the graph using the equation R = A*e^(B/T), where R is resistance, A and B are constants, and T is temperature in Kelvin.

5. What are some common applications of thermistors?

Thermistors are commonly used in temperature control systems, such as in ovens, refrigerators, and air conditioners. They are also used in medical devices, automotive applications, and industrial processes where precise temperature measurements are necessary.

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