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# Wheatstone Bridge

In order to learn about the world around them, scientists utilize a variety of skills. They observe the world around them and gather data with their senses. A simple observation might be determining the texture and colour of an object. A scientist will need to take measurements if he or she wants to learn more about a substance. Taking measurements is a crucial aspect of science. Research and theory formation is impossible without measurements.

Resistance is an important part of an electrical circuit, and thus the study of resistances is very important. The measurement of the unknown resistances is important to calculate the current flowing in a circuit, and furthermore, these calculations will help to understand the rest of the electrical circuits and the system as a whole.

## How do you describe Wheatstone Bridge?

A Wheatstone bridge is also known as a resistance bridge. This is a very useful and easy way of calculating unknown resistances by balancing two legs of a circuit. The circuit has one leg whose resistance is unknown. Sir Charles Wheatstone popularised the Wheatstone bridge in 1843 after William Hunter Christie invented it in 1833.

A Wheatstone Bridge Circuit consists of two known resistors, one unknown resistance and one variable resistance. Because this bridge provides accurate measurements, it is extremely reliable.

## The Structure of Wheatstone Bridge

Circuits based on Wheatstone bridges consist of four arms, two of which contain known resistances, while the other two contain unknown resistances and variable resistances. In addition to a galvanometer, the circuit also has an electromotive force source. The connection of the galvanometer is at points c and d, the emf source is connected between points a and b. The potential difference across the galvanometer determines the current that flows through it.

## Describe the Wheatstone Bridge Principle.

A Wheatstone bridge works on the principles of null deflection, which means their resistance ratio is equal, and there is no current flow. Under normal circumstances, the bridge is not balanced, so current flows through the galvanometer. However, the bridge is balanced if no current passes through the galvanometer. It is possible to adjust the variable as well as known resistances to attain this condition.

## Wheatstone Bridge Formula

The Wheatstone bridge formula is as follows:
R= PS/Q
Where,

• R represents an unknown resistance
• S stands for the standard arm of the bridge
• P and Q are the ratios of bridge arms

## Application for Wheatstone Bridge

• Low resistance is measured using the Wheatstone bridge.
• An operational amplifier and a Wheatstone bridge measure physical parameters such as temperature, light, and strain.
• Devices based on Wheatstone bridge variations measure impedance, inductance, and capacitance.

## Limitations of the Wheatstone Bridge

• Leads and contacts have a significant resistance at low resistance levels, which introduces errors.
• When measuring high resistance, the measurement presented by the bridge is so large that any imbalance does not affect the galvanometer.
• As a consequence of the current passing through the resistance, the resistance changes, the resistance value can even permanently change by excessive current.

Ques: What is your opinion of Wheatstone Bridge?
By balancing the two legs of the Wheatstone bridge circuit, the resistance bridge calculates the unknown resistance. There is a component for the unknown resistance in one leg.

Ques: How do you define the Wheatstone Bridge Principle?
The Wheatstone bridge operates primarily on the principle of null deflection, in which no current flows through the circuit, and the resistance ratio is equal.

Ques: How long does it take for the Wheatstone Bridge to be balanced?
When no current flows through a Wheatstone bridge, it is said to be in a balanced state. The known resistance and variable resistance work together to achieve this condition.

Ques: Is the Wheatstone Bridge unbalanced on its construction?
Current flows through the galvanometer when the bridge is in an unbalanced state under normal conditions.

Ques: Could you please explain the limitations of the Wheatstone Bridge?
During low resistance measurements, the resistances of the leads and contacts become important and introduce errors.

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