Question

What is the electrical resistivity of a material? What is its unit? Describe an experiment to study the factors on which the resistance of conducting wire depends.

Answer 1

A conductor's resistivity is an intrinsic quality that opposes the flow of electric current. Also, every material's resistivity is distinct.

The SI unit is $\Omega \mathrm{m}$.

Experiment to study the factors on which the resistance of conducting wire depends:

A nichrome cable, a torch lightbulb, a $10\mathrm{W}$ bulb, an ammeter ($0–5A$range), a plug key, and some interconnecting wires are all required.

1. As illustrated in Figure, directly connect dry cells of $1.5\mathrm{V}$ each in series with the ammeter, establishing an X.Y gap inside the circuit.
2. Resistance is shown to be materially dependent on the conductor.
3. The resistance would be determined by the length of the conductor.
4. Resistance is proportional to the cross-sectional area.
5. Connect the nichrome cable throughout the X.Y spacing to complete the circuit. Insert the key.
6. Make a note of the ammeter reading. Put the key out of the plug.
7. Substitute the nichrome wire well with the torch bulb inside the circuit as well as to measure the current through all of it using an ammeter.
8. Resume the previous step with the $10\mathrm{W}$ bulb throughout the XY gap.

Therefore, you can do this exercise again by leaving any material component in the gap. Take note of the ammeter values in each situation.