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If thermocouple shows a voltage corresponding to the differential temperature bw junctions then why is there still a voltage when you keep both the junctions at the ambient temperature?
Wiki User
∙ 13y ago
A: THERMOCOUPLE has the characteristic of both negative and positive temperature a room temperature it is still sensing the temperature it will not go to zero except for a specific temperature and that will change for each metal used
Wiki User
∙ 13y ago
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Working of thermocouple?
A device for accurate measurement of temperature difference between two junctions. A thermocouple consists of two dissimilar metals joined at two joints in a loop so that the difference in voltage can be measured. If the temperature of one junction is known, the other junction temperature can be calculated. Since voltage changes in proportion to temperature, the voltage difference indicates temperature differences.
What is device used to convert temperature in to voltage?
temperature sensorAnswerA thermo-voltaic junction, or thermo-voltaic pile, is used for this purpose. A thermo-voltaic junction consists of two dissimilar metals connected together; as the temperature increases, an increasing potential difference arises between the two metals. A thermo-voltaic 'pile' is a number of thermo-voltaic 'junctions' connected in series.
Why is the UJT 2N2646 so called?
Here 2 refers to 2 junctions, N - npn type, 2646 - device id number. Though it have one junction, it has been named to have 2 junctions, as it can act as good transistor
What are gap junctions?
are formed by a ringlike connexon which consist of six transmembrane proteins are arranged somewhat like the segment of an orange
Is bipolar transistor is made up of one NP junction?
no, 2 junctions. NPN or PNP
How can thermocouple measure the temperature?
Thermocouples are two junctions of two dissimilar metal conductors. One junction is the sensing junction and the other is the reference junction. The voltage between the two junctions depends on the temperature difference between the junctions (Seebeck effect). The voltage can be measured and the temperature difference determined based on known readings of the voltage produced by the metals. If the temperature of the reference junction is known, then the temperature of the sensing junction can be calculated.
Is thermocouple a temperature measuring device?
No, by itself a thermocouple can only measure temperature difference between two points (junctions) in a circuit. To use a thermocouple as a temperature sensor, you must know the temperature of one junction by some other means. Often an additional temperature sensor is used. However, in some applications temperature difference is enough. For example, in gas appliances a thermocouple detects presence of a flame because the flame is much hotter than room temperature-- you don't need to actually measure the flame temperature. ====================== Yes, it is. If you look up "thermocouple" in Wikipedia, you will find a very detailed explanation of how and why they work.
Working of thermocouple?
A device for accurate measurement of temperature difference between two junctions. A thermocouple consists of two dissimilar metals joined at two joints in a loop so that the difference in voltage can be measured. If the temperature of one junction is known, the other junction temperature can be calculated. Since voltage changes in proportion to temperature, the voltage difference indicates temperature differences.
How is thermocouple WORKING?
A thermocouple is a thermometer made by using two wires of different metals in a circuit. Two junctions are then formed between the different metals-- one of which is joined to the object having the temperature to be measured and the other is joined to an object having a fixed temperature. An measurable voltage proportional to the temperature difference is generated in the loop.
What is a thermocouple thermometer?
Thermocouple is made up with the junction of two different metals(e.g. antimony and bismuth). This is the device used to measure the temperature due to the fact that when two junctions are placed at different temperature a potential difference developed (thus electrical signal) which is proportional to the difference in the temperature of the two junction. This is very sensitive device.
Describe how a liquid thermometer and a thermocouple are the same and how they are different?
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.
How do you convert output voltage of thermocouple into temperature?
You need to know the temperature of the reference junction and the voltage difference between the reference and sensing junctions. First, you convert the reference temperature to a voltage using the reverse equation or table for your thermocouple type. Then you sum that voltage with the measured voltage. Finally, you convert the summed voltage back to a temperature using the equation or table for the thermocouple type you are using. If the reference junction is at zero degrees C, you can skip the reference summing part. Before computer processing was easy and cheap, the reference junction was often kept in an ice water bath for that reason.
Difference between thermistor and temperature sensor?
A thermistor is a temperature measuring device which acts like a temperature sensitive resistor. It is an active device that requires a current flow to measure its resistance so that the temperature may be calculated and/or displayed. A thermocouple is a device composed of two dissimilar metals fused together. An electrical potential occurs across the junction of the metals. As the potential is influenced by the temperature of the metal junction the output voltage can be measured and calibrated to show the temperature at the joint. Both devices may be employed to measure the temperature within a fixed space, or on a probe to measure the temperature at a remote point or points.
How thermocouple thermometer works?
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.
Does a thermocouple have to touch at the tip or sides to operate correctly?
All thermocouples (whether type J, type K, type T, etc.) measure the difference in temperature between the Tip (junction between two different metals), and the other end of the thermocouple wire, often referred to as the "cold junction." There must be two such junctions somewhere for the thermocouple to operate correctly; typically the measurement junction is at the tip. To measure the temperature of some thing, try to put that junction as close as possible to that thing. However, since the thermocouple is metallic and the measurement relies on detecting tiny voltages, connecting the tip electrically to a metallic surface could affect the measurement. For that reason thermocouples often have insulated tips.
Cylinder head temperature of aircraft engine?
CYLINDER HEAD TEMPERATURE The engine temperature can have a dramatic: impact on engine performance. Therefore, most reciprocat- ing engine powered aircraft are equipped with a cylinder head temperature (CHT) gauge that allows a pilot to monitor engine temperatures. Most cylinder head temperature gauges are gal- vanometer-type meters that display temperatures in degrees Fahrenheit. If you recall from your study of electricity, a galvanometer measures the amount of electrical current produced by a thermocouple. A thermocouple is a circuit consisting of two dissimi- lar metal wires connected together at two junctions to form a loop. Anytime a temperature difference exists between the two junctions, a small electrical current is generated that is proportional to the tem- perature difference and measurable by the gal- vanometer. Typical dissimilar metal combinations used are iron and constantan. or chromel and alumel. Since a thermocouple generates its own electrical current, it is capable of operating indepen- dent of aircraft power. The two junctions of a thermocouple circuit are commonly referred to as a hot junction and a cold junction. The hot junction is installed in the cylin- der head in one of two ways; the two dissimilar wires may be joined inside a bayonet probe which is then inserted into a special well in the top or rear of the hottest cylinder, or the wires may be imbedded in a special copper spark plug gasket. The cold junc- tion. or reference junction, on the other hand, is typ- ically located in the instrument case.
How Do Thermocouplings Work?
A thermocouple produces a voltage when its two junctions are at different temperatures. Measuring the voltage determines the difference in temperature. Thermocouples are used for a wide range of sensing applications in industry, automotive, and appliances. Because a thermocouple is only two wires welded together, it is very rugged. =========================== A thermacouple keeps natural gas and other household appliances from creating a gas leak. This can be dangerous as a gas leak to lead to a explosion and serious injury.
