Electronics - Voltage and Current - Discussion

A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting overcurrent protectors, and self-regulating heating elements.

Rheostat-Current controling device with resistance coil
Potentiometer-Votage varing and measuring circuit
Photoconductive cell- Produces current when light incident on it

All the above have less temperature coefficents.

Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range, typically −90 °C to 130 °C.

Thermistor is a temperature measuring device.

Temp=thermal; so it is thermistor.

Thermistors can be PTC or NTC according to the temperature.

Sundar is correct. There is NTC and PTC types.

It is well known that resistance of metallic conductors increases with temperature, while that of semiconductors generally decreases with temperature. Resistance thermometers employing metallic conductors for temperature measurement are called Resistance Temperature Detector (RTD) , and those employing semiconductors are termed as Thermistors.

The NTC thermistors is more common. Essentially, they are made from oxides of iron, manganese, magnesium etc.

The Positive Temperature Coefficient (PTC) thermistor have limited use and they are particularly used for protection of motor and transformer widings.

They have low and relatively constant resistance below a threshold temperature TR, beyond which the resistance increases rapidly. The PTC thermistors are made from compound of barium, lead and strontium titanate.

To produce the heat that is thermal. The resistor depend on thermal. So its known as thermistor.

What is a need to measure the internal temperature of electical components?

It is to used measure the internal temperature of electical components.

Thermistors is a type of resister whose resistances varies significantly with temperature. Temperature increasing resistances decreasing.