### Factors on which Resistance of a conductor depends:-

**The Electrical Resistance of a conductor depends on the following factors:-**

**Length of the conductor.****Area of the cross-section of the conductor(or thickness of the conductor).****Nature of the material of the conductor.****The temperature of the conductor.**

**LENGTH-** **Resistance is directly proportional to length of the conductor.** **i.e. R ∝ l**

**AREA OF THE CROSS-SECTION-** **Resistance is inversely proportional to the area of the cross-section.** **i.e. R ∝ 1/A**

**TEMPERATURE-** **The Resistance of all pure metals increases on raising the temperature; and decreases on lowering the temperature.**

**Combining all we get:-** **R = ρ(l/A)** **R=Resistance of the conductor.** **ρ(rho)=Resistivity of the conductor.(It is the constant)**

**l=length of the conductor.**

**A=Area of the cross-section of the conductor.**

### Resistivity:-

**where ρ (rho) is a constant of proportionality and is called the electrical resistivity of the material of the conductor.****The SI unit of resistivity is Ω m.****The metals and alloys have very low resistivity in the range of 10**^{-8} Ω m to 10^{-6} Ω m.**Both the resistance and resistivity of a material vary with temperature.**