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

• Resistivity is an inherent property of a conductor which resists the flow of electric current. Resistivity of each material is unique. 
• SI unit of resistance is Ωm.

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

• Take a nichrome wire, a torch bulb, a 10 W bulb and an ammeter (0 – 5 A range), a plug key and some connecting wires. 
• Set up the circuit by connecting four dry cells of 1.5 V each in series with the ammeter leaving a gap XY in the circuit, as shown in Fig.

Observation: 

• It is observed that resistance depend on material of conductor.
• Length of conductor determines resistance
• Resistance depends on area of cross section.