Resistance depends on
Material of conductor
The resistance of a metallic conductor increases as the temperature increases e.g. copper
The resistance of a semiconductor/insulator decreases as the temperature increases e.g. thermistor.
Resistance of a uniform conductor is directly proportional to its length.
i.e. R L
Resistance of a uniform conductor is inversely proportional to its cross-sectional area.
i.e. R 1
The material also affects the resistance of a conductor by a fixed amount for different materials. This is known as resistivity ().
R = L = constant of proportionality
A Unit: ohm meter m
= Rd 2 (For a wire with circular cross-sectional area)