This experiment is about measuring the temperature with the help of a thermistor. In this experiment, the temperature of metals measured with the help of a Thermistors. Thermistors used to measure the temperature because they give an accurate value. It is one of the most sensitive and fastest temperature measuring devices. It works on the principle of resistance. The measurement that obtained compared with the time taken with the help of different temperature measuring devices to check which gives an accurate value in a short time. To perform this experiment, different equipment such as a Pentium-Based computer containing screen, data acquisition board, thermal heater, water, thermometer, Thermistor, power supply, and set of connectors used. The results obtained show that thermistors are reliable and effective temperature measuring instruments.

Introduction of thermistor

                A thermistor called the thermal resistor is a kind of resistor whose electrical oppositional changes when the temperature changes. Many resistors change their resistance values slightly with the change of temperature, but in the case of thermistors, it is very sensitive to any temperature change.

 Figure 1: Thermistors

They are very accurate when a precise reading of temperature is required. Thermistors produced of semiconductors, which means they hold good resistance than bearing off materials, quite lower resistance breaking up materials. The inviting between a thermistor’s temperature and its opposition is exceptionally structured upon the materials from which it crystalized.

Thermistors formed of potential oxides, binders, and stabilizers, pressed into wafers, and then downgrade to chip length, left in disc form, or made into another shape. The unique ratio of the composite substances governs their resistance/temperature “curve.” Manufacturers typically manipulate this ratio with first-rate accuracy, because it determines how the thermistor will function.

Figure 2: Working of Thermistors

The working principle of thermistors is very simple, as the resistance of thermistors is dependent on temperature. If somehow the exact relation of how resistance changed by the change of temperature known then only by measuring the resistance of the thermistor the exact value of temperature determined.

The equation for the relationship between temperature and resistance in a thermistor is as follows:

                      Where ‘RT’ represents resistance at ‘T’ temperature, and likewise ‘R0’ represents resistance at ‘T0’ temperature, here ‘T0’ is ambient temperature normally 25 degrees centigrade, here ‘β’ is constant, and whose values change with the change of temperature. The temperature and time constant measured in this lab.

Method of thermistor

               Thermistors are temperature touchy semiconductors that show off a large alternate in resistance over an exceptionally small variety of temperatures. There are two foremost styles of thermistors: fantastic temperature coefficient (PTC) and negative temperature coefficient (NTC). NTC thermistors exhibit the function of resistance falling with growing temperature. A thermistor is similar to an RTD; however, a semiconductor cloth used in place of a metallic. A thermistor is a solid nation device and has large sensitivity than does an RTD. The time that this thermistor takes in measuring the temperature is measure in this lab. The measurements take at standard temperature and pressure and the reading taken only once. The instruments that were use in taking these measurements a thermistor and stopwatch which were use to measure the time taken.

The following steps were taken to find measurement:

  • Placed the thermistor and boiled water (by using of the heater) along with the mercury thermometer in the beaker.
  • Kept the switch closed.
  • Noted the time taken with help of a stopwatch from ambient temperature to the boiling temperature of the water.

Results and Discussion:

The measurements that were obtained in the experiment are as below:

Sr. NoTemperature Measuring DeviceAmbient Temperature (Centigrade)Measuring Temperature (Centigrade)Time Taken (s)

Table 1 Temperature measurement with Thermistor

The time was scaled with the support of a stopwatch. The graph of the relation of resistance of the thermistor to the increase in temperature is as below. It shows the decrease in resistance of the thermistor with the increase of temperature. The governing equation for this experiment is as follows.


This lab was about effectively calculating temperature and the time that it takes to measure that temperature with the help of a thermistor. Thermistors, derived from the time period thermally sensitive resistors, are a complete and fee-effective sensor for measuring temperature. Available in 2 kinds, NTC (poor temperature coefficient) and PTC (fine temperature coefficient), it’s far from the NTC thermistor that is usually use to measure temperature.  In this experiment, the time constant is measured, and then it is compared with the time constant of other temperature measuring devices to check which apparatus is suitable for which operation and also which takes less time.

Abdul Samad Khan


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