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.
