What are the Applications and Limitations of Wheatstone Bridge?
In order to find an unknown resistance in a circuit, the Wheatstone bridge is actively used. And it is very important to solve various types of problems and questions that involve resistors, and other circuits. So, it is very important for the students to understand the working of Wheatstone Bridge. And therefore, to help you out, here in the article below, we will provide a comprehensive description of Wheatstone Bridge.
Principle of Wheatstone Bridge
The Basic Principle of Wheatstone Bridge is the Principle of Null Deflection. According to this principle, there is no current present in this circuit, and the ratio of resistances is said to be the same. Moreover, at first, the bridge in the circuit, as shown in the diagram, exists in an unbalanced condition, and they can find the current is indeed flowing through the galvanometer. However, in order to keep the bridge in a balanced condition, there should not be any current flow in the circuit. Although to achieve this balanced position, it is needed to adjust the variable resistance and known resistance in the circuit.
Applications of Wheatstone Bridge
In order to measure the low resistance in a circuit.
Other important quantities such as Capacitance, Impedance, and Inductance, can also be calculated using Wheatstone Bridge.
By using an optional amplifier, in the Wheatstone bridge, we will be able to measure physical parameters like Strain, Light, and Temperature.
Limitations of Wheatstone Bridge
There are certain limitations to all types of principles in Physics, including the Wheatstone Bridge.
Excessive current flow in the Wheatstone Bridge may result in a permanent change in the value of resistance.
When low resistance is applied, leads and contacts in the circuit will cause an error, and their values will attain constant.
And in terms of high resistance, the measured values are off-charts, then the galvanometer is considered to be in imbalance.
The basic Wheatstone Bridge consists of four resistive arms forming a diamond shape with a voltage source connected across one diagonal and a galvanometer connected across the other diagonal. The bridge is typically balanced when the ratio of the resistances in one pair of arms equals the ratio in the other pair.
Balancing Principle: When the bridge is balanced, no current flows through the galvanometer. This occurs when the ratio of resistances in one pair of arms is equal to the ratio in the other pair. Mathematically, this condition can be expressed as
Measurement: By varying one of the resistances in the bridge (often done with a variable resistor or potentiometer), the bridge can be unbalanced. The amount of unbalance can be measured by the deflection of the galvanometer. This deflection is directly proportional to the unknown resistance being measured.
Applications: Wheatstone Bridges are extensively used in various fields. For instance, in strain gauge applications, a strain gauge is connected to one of the resistive arms. When subjected to mechanical stress, the strain gauge's resistance changes, causing an imbalance in the bridge. By measuring this imbalance, one can determine the strain on the object to which the gauge is attached.
Temperature Compensation: Wheatstone Bridges are also employed in temperature sensors. Thermistors or resistance temperature detectors (RTDs) are used as the variable resistors. Changes in temperature alter the resistance of these devices, leading to an imbalance in the bridge. By measuring this imbalance, precise temperature readings can be obtained.
Advantages: Wheatstone Bridges offer high accuracy and sensitivity, making them invaluable in precision measurements. They can measure small changes in resistance with great precision, making them suitable for a wide range of applications requiring accurate measurements.
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