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.