Electricity and Magnetism - Electrical quantities

Electric Charge ($Q$): The fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. It is measured in Coulombs ($C$). The charge of a single electron is approximately $-1.6 imes 10^{-19} C$.

Electric Current ($I$): The rate of flow of electric charge. It is defined as $I = \frac{Q}{t}$ and measured in Amperes ($A$), where $1 A = 1 C/s$. Conventional current flows from positive to negative, whereas electrons flow from negative to positive.

Potential Difference ($V$): The work done ($W$) per unit charge ($Q$) in moving a charge between two points in a circuit. It is measured in Volts ($V$), where $1 V = 1 J/C$.

Electromotive Force (e.m.f.): The total energy supplied by a source (like a battery) per unit charge as it moves around a complete circuit. It is also measured in Volts ($V$).

Resistance ($R$): The opposition to the flow of electric current. According to Ohm's Law, for an ohmic conductor at constant temperature, the current is directly proportional to the potential difference, leading to $V = IR$. Resistance is measured in Ohms ($\Omega$).

Resistivity ($\rho$): An intrinsic property of a material that quantifies how strongly it opposes the flow of electric current. Resistance $R$ depends on resistivity, length ($L$), and cross-sectional area ($A$).

Electrical Power ($P$): The rate at which electrical energy is converted into other forms of energy. It is measured in Watts ($W$).