Determination of resistivity - Physics Laboratory Practical Experiment
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
Observations:
(i) To find the resistance: (ii) To find the diameter of the wire using screw gauge:
%20To%20find%20the%20diameter%20of%20the%20wire%20using%20screw%20gauge.jpg)
Calculations:
Radius of the wire, r = diameter/2 = _____________ m
Area of cross section of the wire, \( A = \pi r^2 \) = ____________ m2
Length of the wire L = __________ m.
Resistivity of the material of the wire = 
= __________ Ω m
Result:
The resistivity of the material of the wire = __________ Ω m