What is electrical resistivity of a material? What is its unit? Describe an experiment to study the factors on which the resistance of conducting wire depends.
The inherent property of a conductor because of which it resists the flow of electric
current is called resistivity. Resistivity for a particular material is unique.
The SI unit of resistivity is Ωm (Ohm metre).
Experiment to study the factors on which resistance of conducting wire depends:
• Take an ammeter, electric cell, plug key, nichrome wire and wires of different materials.
• Make the circuit as shown in figure.
• Start the experiment with nichrome wire. Attach it in the circuit and take ammeter reading.
• Change the length of nichrome wire and take ammeter reading.
• Change the thickness of nichrome wire and take ammeter reading.
• After above steps, use copper wire for the experiment. Attach a copper wire in the circuit and take ammeter reading.
• Change the length of copper wire and take ammeter reading.
• Change the thickness of copper wire and take ammeter reading.
• Repeat above steps with wires of different materials.
Observations:
• It is seen that resistance depends on material of conductor.
• Resistance depends on length of conductor.
• Resistance depends on area of cross-section.
