DETERMINATION OF RESISTIVITY
Practical
Answers
Explanation:
DETERMINATION OF RESISTIVITY
Objective:
To determine the resistivity of the material of the given coil of wire.
Equipment required:
A coil of wire, screw gauge, a metre scale, battery, key, ammeter, voltmeter, rheostat and connecting Wires.
Formula:
The resistivity of the material of the coil of wire is
Where A is the area of cross section of the wire (m2)
L is the length of the coil of wire (m)
R is the resistance of the coil of wire (ohm)
Circuit Diagram:
Procedure:
· Connect the battery, ammeter, given wire, rheostat and key in series, as shown in the circuit diagram.
· Connect the voltmeter in parallel to the unknown resistor.
· Close the key and hence the circuit is closed.
· Adjust the rheostat such that the ammeter reads a current of 0.5 ampere.
· Note down the potential difference across the resistor as shown by the voltmeter.
· Adjust the rheostat and change the current in steps of 0.5A (that is 0.5A, 1.0A, 1.5A, etc.).
· For each current, note down the corresponding potential difference as shown by the voltmeter.
· Tabulate the observations.
· Measure the diameter of the wire using a screw gauge.
· Measure the length of the coil using metre scale