Electrostatic Potential and Capacitance

Vocabulary flashcards covering the fundamental concepts of electrostatic potential, potential energy, conductors, dielectrics, and capacitance from the textbook transcript.

Conservative forces

Forces for which the work done in moving a body between two points is independent of the path taken and depends only on the initial and final positions, allowing the work to be stored as potential energy (e.g., spring, gravitational, and Coulomb forces).

Electrostatic potential energy difference ($\Delta U$)

Defined as $\Delta U = U_P - U_R = W_{RP}$, it is the work required to be done by an external force in moving (without accelerating) a charge $q$ from point $R$ to point $P$ in an electric field.

Electrostatic potential ($V$)

The work done per unit positive charge in bringing a unit test charge (without acceleration) from infinity to a specific point in a region of electrostatic field.

Electron volt ($eV$)

A unit of energy equal to $1.6 \times 10^{-19}\,J$, which is the energy gained by an electron when accelerated by a potential difference of $1\,\text{volt}$.

Equipotential surface

A surface with a constant value of electrostatic potential at all points, characterized by the property that the electric field at every point is normal to the surface.

Electrostatic shielding

A phenomenon where the electric field inside a cavity of a conductor is always zero, protecting sensitive instruments inside from external electrical influences.

Dielectrics

Non-conducting substances that have no (or negligible numbers of) charge carriers and develop a net dipole moment when placed in an external electric field.

Non-polar molecules

Molecules in which the centers of positive and negative charges coincide, resulting in no permanent (or intrinsic) dipole moment (e.g., $O_2$, $H_2$).

Polar molecules

Molecules in which the centers of positive and negative charges are separated even without an external field, giving them a permanent dipole moment (e.g., $HCl$, $H_2O$).

Polarisation ($P$)

The dipole moment per unit volume of a dielectric material, which for linear isotropic dielectrics is related to the field by $P = \epsilon_0 \chi_e E$.

Electric susceptibility ($\chi_e$)

A constant characteristic of a dielectric medium that describes its ability to become polarized in response to an electric field.

Capacitance ($C$)

The constant ratio of the charge $Q$ on a conductor to the potential difference $V$ ($C = \frac{Q}{V}$), which depends only on the geometrical configuration of the conductors and the insulating medium.

Farad ($F$)

The SI unit of capacitance, defined as $1\,\text{coulomb volt}^{-1}$ ($1\,F = 1\,C\,V^{-1}$).

Dielectric strength

The maximum electric field that a dielectric medium can withstand without the breakdown of its insulating property; for air, this is approximately $3 \times 10^6\,Vm^{-1}$.

Parallel plate capacitor

A capacitor consisting of two large plane parallel conducting plates of area $A$ separated by a small distance $d$, with a capacitance given by $C = \frac{\epsilon_0 A}{d}$ in vacuum.

Dielectric constant ($K$)

The dimensionless ratio of the permittivity of a substance to the permittivity of vacuum ($K = \frac{\epsilon}{\epsilon_0}$), also defined as the factor by which capacitance increases when a dielectric is inserted.

Energy density ($u$)

The energy stored per unit volume of space in an electric field, given by the expression $u = \frac{1}{2}\epsilon_0 E^2$.

Superposition principle (Potential)

The principle stating that the potential at a point due to a system of charges is the algebraic sum of the potentials due to individual charges ($V = V_1 + V_2 + ... + V_n$).