Difference between thermistor and thermocouples

Thermistor definition

A thermistor is a type of  variable resistor that is temperature sensitive .

How thermistor works?

When its temperature coefficient is negative,the resistance changes inversely with temperature. When its temperature coefficient is positive the resistance changes directly with temperature.

The resistance of a photo-conductive cell changes with a change in light intensity.This cell also has a negative temperature coefficient. Symbols for both of these devices are shown in below figure.

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