How does a resistance thermometer works?
Resistance thermometers work by changing resistance with a change in temperature in a repeatable manner. Resistance thermometers are made from a length platinum that is either wrapped around a ceramic or glass core or has been deposited on a ceramic base.
Which law principle working of resistance thermometer is based on?
According to Ohm’s law, at a constant current the voltage at the measuring conductor varies depending on the electrical resistance (and thus on the temperature). In this way, the measured voltage or voltage change can be used to determine the temperature.
What is the working principle of platinum resistance thermometer?
Definition: The platinum thermal resistance (PTR) uses platinum for determining the temperature. It works on the principle that the resistance of platinum changes with the change of temperature. The thermometer measures the temperature over the range of 200°C to1200°C.
What is the resistance of a thermometer?
The length and diameter of the platinum wire used in a thermometer are often chosen so that the resistance of the device at around 0 ºC is 100 ohms. Such a sensor is a called a PT100 sensor, and its resistance changes by approximately 0.4 ohms per ºC.
What is the working principle of thermocouple?
The operating principle of the thermocouple is based on the Peltier effect. The thermocouple circuit consists of two metals joined together to form two junctions of different temperatures. A Peltier emf is generated due to the difference in temperatures of the two junctions of the circuit.
What is RTD state its applications?
The term RTD stands for Resistance Temperature Detector. This sensor is also known as Resistance thermometer. This sensor is used to measure the temperature. Usually, they are available as a length of fine wire made of platinum nickel or copper, wrapped around a ceramic or glass core.
Who invented resistance thermometer?
(later Sir William) Siemens
The resistance thermometer had in fact been introduced by C. W. (later Sir William) Siemens. In a Bakerian lecture to the Royal Society in 1871 (2) Siemens had explained the theory of the method and described instruments capable of indicating temperatures up to 1000°C.
What is the thermometric properties of resistance thermometer?
Explanation : When current passes through a metal wire, as the temperature increases the resistance increases due to vibration of molecules in metal and collision of electrons carrying current.
Who discovered resistance thermometer?
The discovery that the electrical resistance of a metal varies with temperature was first made by Humphry Davy at the Royal Institution in 1821.
Where are resistance thermometers used?
Due to their accuracy and robustness, they are extensively used as in-line thermometers in the food industry. Within a wide range of temperatures the resistance of metals increases linearly with temperature. The measuring element is usually made of platinum.
What is the principle of thermometer?
These liquid thermometers are based on the principal of thermal expansion. When a substance gets hotter, it expands to a greater volume. Nearly all substances exhibit this behavior of thermal expansion. It is the basis of the design and operation of thermometers.