# What is Wheatstone bridge: Definition and 81 Discussions

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements (in contrast with something like a simple voltage divider). Its operation is similar to the original potentiometer.
The Wheatstone bridge was invented by Samuel Hunter Christie (sometimes spelled "Christy") in 1833 and improved and popularized by Sir Charles Wheatstone in 1843. One of the Wheatstone bridge's initial uses was for soils analysis and comparison.

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1. ### B My strain gauge on a cantiliver beam is reading 0.040V before force is applied...

i connect strain gauge on cantiliver beam and getting reading 0.040v before force applied , the theory said that bridhe should be balance mean=0 1) does 0.040 acceptable to carry on work or 2) how can i make it to 0so that it balanced
2. ### How to connect this strain gauge?

recently i bought this strain guage where vender said it is 4bridge, i am not sure how to connect this in wheatstone bridge , i have 120 ohms resistors, and 120ohm strain gauge. please need guide thank you.
3. ### Wheatstone bridge with four active strain gauges - extension cable length compensation formula

Suppose a Wheatstone bridge with four equal active strain sensors (350 ohm each). The output nodes are connected to a high impedance instrumentation amplifier, so no current draw from there. The bridge is placed at consiberable distance from the exitation voltage source (and the amplifier), so...
4. ### Wheatstone bridge and conditions for current to flow between 2 points

Hello, I was reflecting on the functioning of a balanced Wheatstone bridge circuit: Point C and D are at the same electric potential V (zero potential difference). Even if they are connected by an ideal zero resistance wire, current will not split at either node C or D to flow through that...
5. ### Modification of Wheatstone Bridge

I want to ask what the total resistance of the circuit will be if R2 is removed and being replaced with ideal wire. I think R1 and R3 will be parallel → let this be R6 R6 will be series with R4 → let this be R7 Then R7 will be parallel to R5 Is that correct? Thanks
6. ### How to do the calculations for a Wheatstone Bridge

I know at balanced condition, the current flowing through galvanometer = 0 and R1 . Rx = R2 . R3 What I want to ask is how to analyze the circuit until we can conclude the current will be zero. I have learned about Kirchhoff's 1st and 2nd law and also about potential divider. I am guessing...

8. ### Wheatstone Bridge: Substitution Resistance Formula Derivation?

Hello, In high school, I had been taught about finding substitution resistance from Wheatstone bridge. The formula: a. If the cross product of ##R1## and ##R3## is same as ##R2## and ##R4##, the galvanometer in the middle (##R_5##) can be omitted and use series-parallel principle to solve for...
9. ### Very basic circuit question about a Wheatstone Bridge

I tried to solve by making 4 ohm and 8 ohm, which I believe are parallel as one effective resistance, and making 6 and 12 ohms which I believe are parallel as one effective resistance, and diving the total of the two effective resistance by the total voltage, but by doing so, I can only find...
10. ### How do I use full-bridge strain gauge circuit to measure F?

Hey all, I am using a Wheatstone bridge with 4 strain gauges as resistors. I have a formula for the output voltage (Vout). My questions is how do I make it so instead of voltage I measure force? Do I simply apply a set max. force (let's say 140N), see what voltage I get (Vout,max) and then use...
11. ### Can a reed switch use a wheatstone bridge/potential divider?

Homework Statement Describe the principle of operation of reed switch and LDR using wheatstone bridge and potential divider arrangement I can't find any website that says a reed switch uses a wheatstone bridge or potential divider arrangement. The only find I have found it that that a magnet...
12. ### Wheatstone Bridge at Null position

Homework Statement Consider the Wheatstone bridge as shown in the following figure, where ##e_0## is the Galvanometer reading. The condition for ##e_0 = 0 ## is called the null condition of the bridge. Using the Kirchhoff's rules, we can show that the condition is ## R_1R_4 = R_2 R_3##. Now I...
13. ### Proof of Wheatstone bridge equation

Homework Statement Prove the following equation: ## \Delta U=\frac {R_1R_4}{(R_1+R_4)^2}(\frac {\Delta R_1}{R_1}-\frac {\Delta R_2}{R_2}+\frac{\Delta R_3}{R_3}-\frac{\Delta R_4}{R_4})E## This is used in Wheatstone bridge Homework Equations [/B] U=RI The Attempt at a Solution This has...
14. ### Find all resistor values in the Wheatstone bridge

Hi, I've got a small physics problem : build an thermometer using the Wheatstone bridge, only knowing the voltage and the middle resistor of the bridge. I need help for the resistors values ; I've finished the rest, which is the relation between temperature and the resistors and the voltage. I...
15. ### Solving Wheatstone Bridge w/ R1=2000, R2=3000, R3=4000 & 12V Battery

Homework Statement Set voltage between 1. a-b; 2- b-c; 3 c-d 4. a-c; if voltage of battery is 12V and R_1=2000 ohms R_2=3000 ohms; R_3= 4000 ohms. (see attached file) Homework Equations voltage=final voltage- innitial voltage resistors in series R_1,2=R_1+R_2 parallel resistors...
16. ### Pt100 with wheatstone bridge

currently i working on RTD sensor using wheatstone bridge...but after i complete the circuit where Ra=Rb=Rc=100ohm wiith RTD pt100...i measure the resistance through multimeter...the value resistance is drop to 78 - 84 ohm..its normal?...or anyone has explanation.. i am also has a problem with...
17. ### Current through left bridge of a Wheatstone Bridge

Homework Statement The ammeter in the Wheatstone bridge of (Figure 1) measures zero current when the resistance Rvar of the variable resistor is set to 189 Ω . What is the current IL through the left side of the bridge? Homework Equations Junction rule: ILeft + IRight = I4 I4 + I2 = I1...
18. ### How to ameliorate this Wheatstone bridge?

Homework Statement Hi everybody! I just ran an experiment testing the accuracy of the Wheatstone bridge, which indeed yielded very small error intervals. However, we then ran a test of reproducibility and found that the deviation between the results was very high! Any idea how that could be...
19. ### Experiment using a Wheatstone Bridge

Homework Statement Determine the unknown resistance using a Wheatstone Bridge. Homework Equations Unknown Resistance = known resistance (100-Length) / Length The Attempt at a Solution I've connected the set up as shown in the pictures but my only concern is, I don't have a resistance box so...
20. ### Wheatstone bridge with capacitances

Homework Statement https://www.physicsforums.com/attachments/circuit-gif.64003/ Basically I am asked to find the equivalent capacitor. Homework Equations C = q/v Conservation of energy. The Attempt at a Solution I have read a lot about this topic and how if they were for example resistor and...
21. ### Wheatstone Bridge: No Current Flow?

In a circuit if the potential difference between two points is zero, no current flows between the two points, right? Or am I wrong? I feel like I am wrong. If I am right, then in a Wheatstone bridge, no current passes through the bridge. Then instead of removing the bridge, why don't we connect...
22. ### How does a Wheatstone Bridge work?

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.
23. ### Calculating current in an unbalanced wheatstone bridge?

I am having troubles understanding how to calculate the current at RSensor when RSensor is 110 Ohms. Any help would be appreciated.
24. ### Current in Wheatstone Bridge

Homework Statement The ammeter in the Wheatstone bridge of measures zero current when the resistance Rvar of the variable resistor is set to 193Ω . What is the current IL through the left side of the bridge? Homework Equations V1 + V2 + V3 + V4 + ... + VN = E Rx = Rvar*R3/R1 The Attempt at a...
25. ### Wheatstone bridge -- Why set all 4 resistances equal?

Can someone explain me,why Wheatstone bridge is most sensitive when all four resistances say A,B,C and D are equal?as far as i know condition for Wheatstone Bridge is A/B=C/D.
26. ### Wheatstone bridge, only one R value known

Problem statement, work done, and equations: I cannot figure how to get the other resistor values, seems like too few knowns A Wheatstone Bridge is often used in sensor circuits and other measurement circuits. The basic circuit is drawn below: In the circuit, Rs is the sensor and might be a...
27. ### Engineering Help with Wheatstone Bridge Strain Gauge Circuit

Homework Statement Given your average Wheatstone Bridge with R1 R2 and R3 unknown resistor values and R4=RG= strain gauge, how to solve for the resistor values given only input voltage and the value of the resistances between the resistors?[/B]Homework Equations Not Sure[/B]The Attempt at a...
28. ### Wheatstone bridge problem unable to understand

Homework Statement The bridge circuit below is used to monitor temperature using a thermometer. The thermometer RT has resistance of 100 Ω at 0°C and a linear coefficient with temperature of 0.005 Ω/°C. What is the sensitivity of the bridge (ΔVOUT/ΔT) around 100 °C for ΔT = 1°C? How does it...
29. ### Thevenin's equivalent of wheatstone bridge

Hi guys, I tried to calculate the Vos and Isc and both of them are zero..so the Thevenin's resistance is 0/0=undefined. How do I calculate the resistance when Vos/Isc fails,such like the wheatstone bridge?
30. ### Wheatstone Bridge Experiment.

Hello Forum, I did an experiment on a Wheatstone bridge. We are to calculate the theoretical resistance of a given set of wires, then by using a value closest to the theoretical we are to set the resistance on a decade box. After the resistances are set we try to find the point on the bridge...
31. ### Resistance Of A Unbalanced Wheatstone Bridge Circuit

Resistance Of An Unbalanced Wheatstone Bridge Circuit How to find the equivalent resistance across the battery (I mean the whole circuit) of a Wheatstone Bridge circuit IF GALVANOMETER CURRENT IS NOT ZERO (i.e. unbalanced circuit)?
32. ### Engineering Wheatstone Bridge Circuit #2

http://i42.tinypic.com/10sfxa1.jpg Im having trouble with the bridge circuit. I see the current has been given 2A So 6.6=3i1+2(i1-i2) 5i1-2i2=6.6 So applying KVL I get 0=4i2+5i1-3(2-i1) 8i2+5i1=6 So using simultaneous equations I get- 5i1-2i2=6.6 5i1+8i2=6 So 10i2=12.6 i2=...
33. ### Advanced Project - Wheatstone Bridge for TCR measurements

Advanced Project -- Wheatstone Bridge for TCR measurements Ok, so I have to do this experiment on my own as part of my coursework this year and I picked something called the temperature coefficient of resistance. I think I basically have to determine the TCR or copper and I'm almost...
34. ### Electronics, Wheatstone bridge, with a twist.

Homework Statement The bridge circuit below is used to monitor temperature using a thermometer. The thermometer RT has resistance of 100 Ω at 0°C and a linear coefficient with temperature of 0.005 Ω/°C. What is the sensitivity of the bridge (ΔVOUT/ΔT) around 100 °C for ΔT = 1°C? How does it...
35. ### AC Excited Wheatstone Bridge

I have a torque meter using a full-bridge Wheatstone bridge (all legs are strain gauges). The bridge has some non-zero, unknown offset (it's old). I would like to strip this offset out prior to signal amplification. My theory is, under DC conditions, the offset exists, which mucks up the...
36. ### Wheatstone bridge arrangement with an ideal wire in middle

Homework Statement I came across this questions in one of the online entrance tests,so i do not remember the exact values,I remembered the arrangement. ________________ |... |...| |... A...C 2v...|--------| (Please ignore the dots,they are to prevent...
37. ### How to connect strain gauge in the form of wheatstone bridge

HAI I am SYED , i am doing my project using strain gauges. Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is (1) Can anyone...
38. ### Wheatstone Bridge with Thevenin's Theorem

Homework Statement http://imageshack.us/a/img685/602/homeworkprobsg29.jpg [Broken]The bridge circuit provides a good illustration of the use of Thevenin's theorem. Find the current through the bridge resistor (50Ω). Homework Equations V = IR source transformations, current division...
39. ### Thevenin equivalent for wheatstone bridge

Hi, can anyone help me on how to find Thevenin equivalent resistances for a Wheatstone bridge configuration? I've searched all over google and youtube, but I haven't been able to fully understand the procedures.
40. ### Yet another Wheatstone bridge with thermistor

Homework Statement So I got a thermistor here and am told that in the range 0-80 celsius the thermistor's resistance is given by Rt = R0 - kT ...whereas R0 = 100 ohms which is the thermistor resistance at 0 celsius. k = 0.5 kohms/celsius. T is of course temperature. The op-amps are ideal and...
41. ### Balanced Wheatstone Bridge

Homework Statement Show that the current in the middle is zero if all the resistors are equal The Attempt at a Solution KVL for left and right: V - R*i1 - R*i2 = 0 V - R*i3 - R*i4 = 0 i1 + i2 = i3 + i4 KCL: i1 + i3 = i2 + i4 i1 + iG = i2 i3 = iG + i4 I must prove that...
42. ### Solving Wheatstone Bridge: Find Detector Current i_d

Homework Statement Find the detector current i_d in the unbalanced bridge in the figure if the voltage drop across the detector is negligible. The source voltage v_g is 180V. Homework Equations The Attempt at a Solution I am not sure what to do, or even how to find the...
43. ### Wheatstone bridge sensitivity

I'm struggling to understand what makes the wheatstone bridge such a good circuit for measuring small resistances. Essentially the bridge is just two voltage dividers and the output voltage is the difference between the two dividers. Ok so the only advantage I can see over a conventional...
44. ### Wheatstone Bridge question

looking for some help for the second part of this question. i got 60 ohms for part one the answer to part 2 shows (delta v = 4.44mv) not sure how to calculate this or what is voltage resolution. regards
45. ### Wheatstone bridge with inductances

Homework Statement Homework Equations Assume we have Vab. Junction Rule: I1 = I3 + I4 => I'1 = I'3 + I'4 I5 = I2 + I3 => I'5 = I'2 + I'3 Loop Rule: V - L1I'1 - L4I'4 = 0 -L1I'1 - L3I'3 + L2I'2 = 0 V - L1I'1 - L3I'3 - L5I'5 = 0 V - L2I'2 - L5I'5 = 0 The Attempt at a...
46. ### Wheatstone Bridge Calculation

Homework Statement A strip of high-strength steel has a length of 30 cm and a cross section of 1 mm by 20 mm. The modulus of elasticity is 200 GPa, and Poission's ratio is 0.25. It is subjected to an axial load of 15,000N. It is instrumented with two axial strain gauges with R=159Ω and a gauge...
47. ### Unbalanced Wheatstone Bridge voltage across resisitors

Homework Statement It is a qualitative problem. No values are given. In an unbalanced Wheatstone Bridge, does the voltage across the resistors R4 and R2 change? In other words is Vr2of balanced bridge=Vr2 of unbalanced bridge? likewse for R4. Homework Equations The Bridge Balance eqn...
48. ### Unbalanced Wheatstone Bridge

In an unbalanced Wheatstone Bridge, does the voltage across the resistors R1 and R2 change? In other words is VR2of balanced bridge=VR2 of unbalanced bridge? I was trying to solve a problem that required qualitative analysis. It says VR2 does not change even though the bridge is unbalanced...
49. ### Norton Transform on a Wheatstone Bridge

I have been trying to find the norton equivalent of a wheatstone bridge with the "bridge" resistor as a the load. The Bridge is unbalanced. How do i find the current through the load when it is shorted to find the norton current? It seems easy , but i haven't found any ways of doing it. I...
50. ### Wheatstone bridge, prove converse.

Homework Statement You are given a standard Wheatstone bridge, prove that the bridge is balanced if and only if R_x = R_3 \frac{R_2}{R_1} . Subindexes depend on the names assigned to each resistance. Proving that if the bridge is balanced THEN the resistors satisfy said relationship is easy...