4.2. Measurements
            4.2.2. Temperature measurement
4.2.2.2. Other thermometers

Other thermometers

Electrical thermometer

Response time varies from 0.1sec to 15sec.

Smaller probes have smaller heat capacity, thus faster response time.

Resistance thermometer

Principle

Electrical resistance of a metal increases linearly with temperature increase.

Example

Advantage

Disadvantage

Thermistor

A solid state thermometer which is composed of fused oxides of certain heavy metal (e.g. cobalt).

Principle

Example

NB: Some metal oxides have positive temperature coefficient (resistance increases with temperature increase)

Advantage

Disadvantage

Thermocouple

Principle

Seebeck effect - at any junction of two dissimilar metals, a small voltage is produced, the magnitude of which depends on the temperature of the junction

46 microvolts per degree Celcius change

Example

Metals such as copper and constantan are used

(Constantan is an alloy of copper and nickel.)

Advantage

Disadvantage

Others

Infrared ear and tympanic membrane thermometer

Principle

Example

Pyroelectric sensor
Thermopile sensor

Advantage

Disadvantage

Keywords:  Thermometer
About
Created20050526
Reviewed20050528


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