(N/A) Electrical resistance is the property of a conductor by virtue of which it opposes the flow of electric current through it. It is defined as the ratio of the potential difference $(V)$ applied across the conductor to the current $(I)$ flowing through it, given by $R = V/I$. The $SI$ unit of resistance is the ohm $(\Omega)$.
The resistance of a conductor depends on the following factors:
$1$. Length of the conductor $(l)$: Resistance is directly proportional to the length $(R \propto l)$.
$2$. Area of cross-section $(A)$: Resistance is inversely proportional to the area of cross-section $(R \propto 1/A)$.
$3$. Nature of the material: Resistance depends on the resistivity $(\rho)$ of the material.
$4$. Temperature: For most conductors, resistance increases with an increase in temperature.