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Ravyan Asro
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I have never understood the concept of the Wheatstone Bridge and how it works. Even the following equations and numericals on this topic of platinum resistance thermometer confuses me a lot... I need help.
You can think of it as a battery with two potential dividers connected across it. When they are both set to give the same voltage, if we connect a meter between the tapping points, it will read zero.Ravyan Asro said:I have never understood the concept of the Wheatstone Bridge and how it works. Even the following equations and numericals on this topic of platinum resistance thermometer confuses me a lot... I need help.
Any reactions?Ravyan Asro said:I have never understood the concept of the Wheatstone Bridge and how it works. Even the following equations and numericals on this topic of platinum resistance thermometer confuses me a lot... I need help.
When it is balanced, the ratios of the two potential dividers are the same, and if three of the resistor values are also known, the third can be calculated using the formulas given previously.Ravyan Asro said:if the bridge is balanced, does it mean that the objective of resistance is fulfilled? thank you for making this doubt a whole lot clear.
I think the clue is in the name Thermo (as in heat / temperature) and Meter (as in measuring device). That is their prime purpose. A standard resistance will be specified at a given temperature and can be used in a wheatstone bridge for measuring other unknown resistances. But the reason for choosing platinum resistance thermometers - as opposed to iron or aluminium resistance thermometers is that platinum doesn't corrode as easily and it maintains its characteristics over a wide temperature range.Ravyan Asro said:electric resistance of a metal wire increases monotonically with temperature and may be used to define a temperature scale. the platinum resistance thermometers are used to measure resistance, can they also be used to measure temperature?
That it is the whole point of a wheatstone bridge isn't it? It is a method of the measuring equipment not loading the circuit under test at the most important time. Not sure if that was the reason it was developed but it is certainly a perk.Let'sthink said:I would like to point out an interesting fact here with regard to balanced wheatstone bridge. Normally if we connect any two points of a complicated circuit by a resistance the effect produced by it depends on the value of the connected resistance. But in the case of a balanced wheatstone bridge you can connect any resistance from zero to infinity between the points across which the bridge is balanced no effect will be produced in any part of the circuit. Zero potential difference has created this incredible thing!
I think the Charles Wheatstone invented the bridge to locate the position of an Earth fault on a telegraph cable. I believe the principle is that when the wires are made into a bridge, the actual resistance of the Earth fault does not influence the distance measurement.Averagesupernova said:That it is the whole point of a wheatstone bridge isn't it? It is a method of the measuring equipment not loading the circuit under test at the most important time. Not sure if that was the reason it was developed but it is certainly a perk.
What do you mean? Could you please draw a diagram of the cable (fault) and bridge?tech99 said:I think the Charles Wheatstone invented the bridge to locate the position of an Earth fault on a telegraph cable. I believe the principle is that when the wires are made into a bridge, the actual resistance of the Earth fault does not influence the distance measurement.
If you look at the Murray Loop Test at this link it will give the diagram you need.tim9000 said:What do you mean? Could you please draw a diagram of the cable (fault) and bridge?
Let'sthink said:I would like to point out an interesting fact here with regard to balanced wheatstone bridge. Normally if we connect any two points of a complicated circuit by a resistance the effect produced by it depends on the value of the connected resistance. But in the case of a balanced wheatstone bridge you can connect any resistance from zero to infinity between the points across which the bridge is balanced no effect will be produced in any part of the circuit. Zero potential difference has created this incredible thing!
Ravyan Asro said:electric resistance of a metal wire increases monotonically with temperature and may be used to define a temperature scale. the platinum resistance thermometers are used to measure resistance, can they also be used to measure temperature?
A Wheatstone Bridge is an electrical circuit that is used to measure an unknown resistance by comparing it to a known resistance. It works by balancing two sets of resistors in a bridge formation, with the unknown resistance in one arm and a known resistance in the other. When the bridge is balanced, the voltage across the center point is zero, indicating that the two resistances are equal.
The purpose of a Wheatstone Bridge is to measure an unknown resistance accurately. It is commonly used in electrical and electronic circuits for this purpose, as well as in strain gauge measurements, temperature sensors, and other applications where precise resistance measurements are needed.
To calculate the unknown resistance, you first need to know the values of the other three resistors in the Wheatstone Bridge. Then, you can use the formula Rx = R2 * (R1 / R3), where Rx is the unknown resistance, R1 and R3 are the two resistors in the same arm as the unknown resistance, and R2 is the resistor in the opposite arm. By adjusting the values of R1 and R3, the bridge can be balanced and the value of Rx can be calculated.
One of the main advantages of using a Wheatstone Bridge is its ability to measure unknown resistances with high accuracy. It is also a simple and straightforward circuit to set up and use, requiring only a few components. Additionally, the Wheatstone Bridge can be used to measure a wide range of resistances, making it a versatile tool in many different applications.
One limitation of the Wheatstone Bridge is that it requires a power source to function, which may not be convenient or feasible in certain situations. Additionally, the accuracy of the measurements may be affected by factors such as temperature changes, stray capacitances, and other external influences. Careful calibration and shielding can help minimize these limitations, but they should be taken into consideration when using a Wheatstone Bridge for precise measurements.