Ohm's Law

The current through a conductor is directly proportional to the potential difference across its ends, provided the temperature remains constant.

$$V = IR$$

where $R$ is the resistance of the conductor, measured in ohms ($\Omega$).

$$R = \frac{V}{I}, \quad 1\,\Omega = \frac{1\,\text{V}}{1\,\text{A}}$$

Factors Affecting Resistance

The resistance of a conductor depends on:

$$R = \rho \frac{l}{A}$$

where:

• $\rho$ = resistivity of the material ($\Omega\,\text{m}$)
• $l$ = length of the conductor
• $A$ = cross-sectional area