# Modification of Wheatstone Bridge

• songoku
In summary: Star.In summary, the total resistance of the circuit will be equal to the parallel combination of R4 and R5 if R1 and R2 are replaced by ideal wires. This is because R3 will be effectively eliminated and the remaining resistors will be in parallel. The Delta-star transformation is not necessary in this scenario. Thank you to Charles Link and Delta2Star for their assistance and clarification.
songoku
Homework Statement
This is not homework, the question just crossed my mind when I was reviewing about Wheatstone bridge. Please see the picture below
Relevant Equations
Series and Parallel circuit

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

I believe you have it correct. :)

I also think you are correct.

If both R1 and R2 are replaced by ideal wire, would I need to use Delta - star transformation?

Something like this:

where:
$$R_A=\frac{R_3 \times R_4}{R_3+R_4+R_5}$$
$$R_B=\frac{R_3 \times R_5}{R_3+R_4+R_5}$$
$$R_C=\frac{R_4 \times R_5}{R_3+R_4+R_5}$$

After that, ##R_A## will be parallel to ##R_B## and the result will be series with ##R_C##

Is that correct? Thanks

No I don't think that's correct , if ##R_1## and ##R_2## are replaced by ideal wires then we shall have ##V_D=V_A=V_B## which means that effectively ##R_3## will also be out of the game. So you ll just have ##R_4## and ##R_5## in parallel. That's what I think.

songoku
Delta2 said:
No I don't think that's correct , if ##R_1## and ##R_2## are replaced by ideal wires then we shall have ##V_D=V_A=V_B## which means that effectively ##R_3## will also be out of the game. So you ll just have ##R_4## and ##R_5## in parallel. That's what I think.
Ah I see

Thank you very much for the help and explanation Charles Link and Delta2

## 1. What is a Wheatstone Bridge?

A Wheatstone Bridge is a type of electrical circuit used to measure unknown resistance values. It consists of four resistors arranged in a diamond shape with two known resistors on one side and two unknown resistors on the other side.

## 2. How does a Wheatstone Bridge work?

A Wheatstone Bridge works by applying a known voltage to the two known resistors and measuring the voltage across the two unknown resistors. By comparing the measured voltage to the known voltage, the resistance of the unknown resistors can be calculated using Ohm's law.

## 3. What is the purpose of modifying a Wheatstone Bridge?

The purpose of modifying a Wheatstone Bridge is to improve its sensitivity and accuracy. Modifications can be made to the circuit to reduce errors caused by temperature changes, increase the range of resistance values that can be measured, and improve the precision of the measurements.

## 4. What are some common modifications made to a Wheatstone Bridge?

Some common modifications made to a Wheatstone Bridge include using a Kelvin Bridge configuration to reduce errors caused by lead resistance, adding a variable resistor to adjust the sensitivity of the circuit, and using a digital voltmeter for more precise measurements.

## 5. What are the applications of a modified Wheatstone Bridge?

A modified Wheatstone Bridge is commonly used in scientific and industrial settings for precise measurements of resistance. It is also used in strain gauges, which measure changes in resistance due to mechanical strain, and in temperature sensors, where changes in resistance are used to measure temperature.

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