Resistance depends on

Temperature

Material of conductor

Length

Cross-sectional area

Temperature

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.

length

Resistance of a uniform conductor is directly proportional to its length.

i.e. R L

Cross-sectional area

Resistance of a uniform conductor is inversely proportional to its cross-sectional area.

i.e. R 1

Material

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)

Temperature

Material of conductor

Length

Cross-sectional area

Temperature

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.

length

Resistance of a uniform conductor is directly proportional to its length.

i.e. R L

Cross-sectional area

Resistance of a uniform conductor is inversely proportional to its cross-sectional area.

i.e. R 1

Material

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)