The physics experiment ‘Resistivity of the  material of the wire’ is an important experiment for class 12 students, particularly CBSE students.The resistivity values of various wires are used in everyday applications like electrical wiring, heating elements, resistors, semiconductors, and material categorization, among others.This experiment exposes class 12 students to the resistivity values of various wires as well as the analysis of their results.

As part of this, the students measure the resistance of the wire, the screw gauge’s zero error, the radius of the wire, and the resistivity values using either Ohm’s law or the meter bridge method, using the proper formula.This practical ensures that the idea of resistivity is understood,its unit, as well as the values for various materials.Let us talk about this issue.

KNOWN RESISTANCE (RIGHT GAP),UNKNOWN RESISTANCE (LEFT GAP) & EXPERIMENTAL SETUP

KNOWN RESISTANCE (LEFT GAP),UNKNOWN RESISTANCE (RIGHT GAP) & EXPERIMENTAL SETUP

RESISTANCE OF THE MATERIAL OF THE WIRE

PROCEDURE

• The meter bridge is an electrical device used to measure the resistance of an unknown resistor.
• It works on the principle of the Wheatstone bridge, which is a circuit with four resistors connected in a specific way. When the bridge is balanced, there is no current flow through the galvanometer.
• To use the meter bridge, first connect the resistors according to the circuit diagram.Then, select a known resistor from the resistance box and place it in the left hand arm of the bridge.
• Once the circuit connections are completed,the jockey is pressed near the end  A and then near end B of the meter bridge wire. If the deflections in the galvanometer are on one side , then there is some fault in the circuit connections.Check for double side deflections in the galvanometer.
• Move the jockey along the meter bridge wire until the galvanometer needle points to zero. 
• The point at which the jockey is located is called the balance point.
• The unknown resistance is calculated using the meter bridge resistance formula

METER BRIDGE – FORMULA

RADIUS OF THE WIRE USING SCREW GAUGE

Screw gauge:

ZERO ERROR OF THE SCREW GAUGE

POSITIVE ZERO ERROR

Negative Zero error

PITCH OF THE SCREW

LEAST COUNT OF THE SCREW GAUGE

DIAMETER AND RADIUS OF THE WIRE

SCREW GAUGE – OBSERVATIONS

TABULAR COLUMN – RADIUS OF THE GIVEN WIRE, SCREW GAUGE

RESISTIVITY OF THE MATERIAL OF THE WIRE

RESISTIVITY

RESISTANCE OF A MATERIAL

RESISTIVITY OF THE MATERIAL OF THE WIRE

RESISTIVITY OF THE MATERIAL OF A WIRE – PROCEDURE

1. The resistance of the given wire is to be calculated using the meter bridge.
2. The principle of the meter bridge is  based on the Wheatstone bridge balancing condition.
3. Using screw gauge, the radius of the given wire is to be determined.
4. The given wire is stretched and  with the help of a meter scale, the length of the wire is to be measured.
5. By applying these values we can calculate the resistivity of the given wire.

CALCULATION: RESISTIVITY OF THE MATERIAL OF A WIRE

RESISTIVITY OF THE MATERIAL OF A WIRE – RESULT

1.The resistance of the given wire using using meter bridge(X) = 2.919 Ohms

2. The resistivity of the material of the given wire = 6.739 X 10^-7 Ohm meter

CONCLUSION

 The above-mentioned practical ‘Resistivity of the material of the wire’ is an important part of the class 12 physics practical curriculum.Students acquire hands-on experience measuring resistivity and learning how it changes for different materials, as well as the solution for material categorization and practical applications and also valuable knowledge for those pursuing careers in engineering or physics.

By participating in this sort of laboratory practical, students hone their analytical and problem-solving abilities, which are crucial in the scientific area.Overall, it is a fun and educational approach to expose kids to the realm of physics and its practical applications.Did you ever spend the majority of your time in your physics lab?