Meter Bridge

Electrical flow is the flow of charged particles, such as electrons or particles, moving along an electrical conveyor or space. It is estimated as the net rate of charge flow through a surface or into a controlled volume. A moving particle is called a charge carrier, and it can be one of several types of particles that depend on a conductor. In electrical circuits, charge carriers are electrons that normally move through wires. In semiconductors, these can be electrons or holes. The charge transporters are treated particles in an electrolyte, but in plasma, an ionized gas, they are particles and electrons. The SI unit of the flow of current is the ampere and it is the progression of electric charge across a surface at the pace of one coulomb each second. A meter bridge is an electrical device that can quantify the value of hidden obstacles. It is made of meter wire with a uniform cross-section. These wires are either nichrome or manganese or constantan because they offer high resistance and low coefficient of temperature disturbance. At the Wheatstone connection, a measuring scaffold or sliding wire connection is planned. This is the most basic and useful use of Wheatstone compounds.

Overview

A meter bridge, also known as a slide wire bridge, is an instrument that works on the principle of a Wheatstone bridge. A meter bridge is used to find the unknown resistance of a conductor, as in a Wheatstone bridge.

Wheatstone bridges, also known as resistance bridges, are used to calculate the resistance of an unknown. This is done by balancing the two different branches of the circuit bridge. One leg has an unknown resistance component. This bridge has two resistors, one with an unknown resistor and the other with a variable resistor. Bridges are considered reliable because they provide accurate measurements. The bridge consists of four arms two of them are known and the other two have one variable and unknown resistance. Also, the bridge circuit includes a galvanometer and a source of electromotive force.

A meter bridge is made of wire 1 m long and equal in cross-section, stretched between two thick metal strips bent at right angles and secured with two gaps through which resistors must be connected. The end to which the wire is fixed is connected to the cell through a key. One end of the galvanometer is connected to a metal strip in the middle between the two gaps. The other end of the galvanometer is connected to a nose that runs along the wire to create an electrical connection.

R is said to be an unknown resistance connected across one of the gaps.

We join a standard known resistance S across the other gap.

Here, the jockey is joined to some point D on the wire, a distance l1 cm from the end A. The portion AD of the wire has a resistance Rcml1, where Rcm is the resistance of the wire per unit centimetre. The portion DC of the wire similarly has a resistance R_cm(100-1₁).
In general, the meter bridge works on the same principle as the Wheatstone bridge.

At balance condition:

Determining the unknown resistance using Meter Bridge

• Gather the instruments and set up connections.
• Select a suitable kind of resistance ‘ R ‘ from the resistance box.
• Now, touch jockey at the point A; we can see that there is a deflection in the galvanometer on one of the sides, then contact the jockey on point C of the wire, now the deflection in the galvanometer has to be on another side.
• Find out the state of the null point having deflection in the galvanometer that becomes zero. Note the length AB (I) BC=(100-I).
• Proceed with this method for several values of the ‘R’.
• Take the balance point where the galvanometer shows a 0 deflection.
• Now, calculate the length of a given wire with the help of ordinary scale and radius of the wire by the utilization of a screw gauge.
• Determine Mean Resistance of Single Unknown Resistance = Total Sum of resistances of Unknown resistance from the above five readings) /5.

Principle of a Meter Bridge

Counter arithmetic rules are the same as Wheatstone linking rules. Wheatstone connections depend on bad evasion rules. For example, no current will flow through the centre arm of the circuit at a point where both arms have the same ratio of protection.

Working on a Meter Bridge

• First move the rider to the endpoints of the wire, that is, A and C.
• Now, start sliding the rider gradually over the wire and cautiously see where the redirection of the galvanometer comes out to be zero from side A.
• If a point isn’t found, take a stab at different obstructions across the extension by changing the opposition on the variable opposition.
• Now, slide the rider over the wire and cautiously check the point on the wire where the redirection of the galvanometer comes out to be zero.
• Then, find out the length of the invalid point utilizing the meter scale appended along the wire. It is considered as the ‘adjusting length’ of the meter connected.

• Let the distance between focuses An and B alone ‘ l1 ‘.
• Let the distance between focuses B and C alone ‘ l2 ‘, where l2=100-l1.
• Finally, the meter connects acts as a Wheatstone connects at the point when the galvanometer shows invalid diversion.

FAQs

What is a meter bridge?

A meter bridge, also known as a slide wire bridge, is an instrument that works on the principle of a Wheatstone bridge. A meter bridge is used to find the unknown resistance of a conductor, as in a Wheatstone bridge.

What is meant by end blunder in a meter connection?

An end error occurs when any of the metric scale sizes do not match the wire start. This happens because of the movement of zero scales or because there is an obstruction in the wire.

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