DETERMINATION OF RESISTIVITY | TENTH STANDARD | PHYSICS | SAMACHEER EDUCATION
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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)
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 and record the readings.
• 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
Calculations:
Radius of the wire, r = diameter/2 = _____________ m
Area of cross section of the wire, A = π r2 = ____________ m2
Length of the wire L = __________ m.
Resistivity of the material of the wire =(A/L)R = __________ Ω m
Result:
The resistivity of the material of the wire = __________ Ω m