Couple means a pair. So two dissimilar metals, for example copper and iron, can be taken. Say two copper rods and one iron rod. Now let us weld them keeping iron in-between the two copper rods.
Two junctions will be formed. If both the junctions are at the same temperature, nothing remarkable happens. If one junction is at a higher temperature than the other, then an emf is produced. This emf can be measured as the voltage difference between the two copper rods. It will be very small, in the millivolt or microvolt range.
If such thermocouples are arranged in series then the emf will be added and so considerable emf could be produced.
This happens due to the Seebeck effect, where an electrical potential is formed between two ends of a conductor if the ends are at different temperatures. It is commonly misstated that a potential is formed at the junction between the two metals, but basic physics is that there can be no potential between two conductors in contact.
The thermocouple does not actually measure temperature, but the temperature difference between two points. If the temperature at one point is known (reference junction) then the temperature of the other point (sensing junction) can be calculated.
A thermocouple measures temperature difference (not temperature). A thermocouple is a pair of dissimilar metals wires twisted together that form two metal-to-metal junctions. When the junctions are at different temperatures a small but measurable voltage difference is produced that indicates the difference in temperature between the junctions. The voltage depends on the type of the two metals, but common types are known and the equations or tables are available.
So if you know the temperature of one junction (the reference junction) and the voltage difference, you can calculate the temperature at the other (sensing) junction.
A thermocouple measures temperature. It can also be used to convert temperature grade into electricity. They do not need external sources of energy to be powered, and as a result of their efficiency, accuracy and ease of manufacturing, the small, common builds are quite cheap. The best part is the color-rating system - depending on the conductors used in the manufacturing plant, they can be rated to measure up to thousands of degrees celsius. They are mostly used in the science and industry fields to measure fuel offset and material combustion.
thermometer, thermocouple, thermodynamics
you use a thermocouple instrument
temperature! A good thermometer, a thermocouple, a thermoresistance, a pyrometer, etc.
Both are used to measure temperature, but by different means. A liquid based thermometer uses the expansion of a liquid with temperature to indicate the temperature, while a thermocouple uses electrical differentials at the junctions of dissimilar metals to do so. So in the case of the liquid thermometer the reading is position of a liquid in a tube, and in the case of a thermocouple it is a voltage measured with a voltmeter. Thermocouples may be better suited to measuring extreme temperatures.
Celsius, Fahrenheit, and Kelvin.
Advantages of using a thermocouple instead of a regular lab thermometer include faster response time, wider temperature range, and higher accuracy. Disadvantages may include higher cost, the need for calibration, and susceptibility to electromagnetic interference.
A thermocouple thermometer is typically used to measure the temperature of a burning matchstick. This type of thermometer can withstand high temperatures and provide accurate readings in extreme heat conditions.
A thermocouple is used instead of a thermometer when the temperature measurement needs to be taken in harsh or high-temperature environments, as thermocouples are more rugged and can withstand extreme conditions. Thermocouples also provide faster response times and can measure a wide range of temperatures compared to traditional thermometers.
the thermometer that works on constant pressure
Very simple answer: to make a hole in a cork or plastic stopper; the scope is to insert a tube, thermocouple, thermometer, etc.
A thermometer measures temperature using a temperature-dependent physical property, such as liquid expansion or electrical resistance. A thermocouple, on the other hand, generates a voltage proportional to the temperature difference between its two junctions, based on the Seebeck effect. Thermocouples are typically used in more extreme temperature environments compared to thermometers.
A thermocouple may be more useful than a regular lab thermometer if you want to measure fairly high temperatures. A disadvantage is that thermocouples may be subject to wear and may not be very accurate or precise. The thermocouple must be calibrated against a known standard before it is used for measurement.