Untitled

Electric Potential

The work done in bringing a unit positive test charge from infinity to a point in an electric field without acceleration.

Potential Difference (V_B - V_A)

The work done in bringing a unit positive charge from one point to another in an electric field.

Electric Potential due to a Point Charge

V = (1 / 4piepsilon_0) * (q / r) for a point charge.

Electric Potential due to a Short Electric Dipole (At Axis)

V = (1 / 403piepsilon_0) * (p / r^2) at its axis.

Electric Potential Energy (E.P.E.)

The energy stored within a system of electric charges due to their relative positions in an electric field.

E.P.E. of a System of Two Point Charges

U = (1 / 403piepsilon_0) * (q1 * q2 / r12).

Work Done in Rotating a Dipole

W = pE * (cos(theta_1) - cos(theta_2)).

Electrostatic Property of a Charged Conductor

Inside a charged conductor, the electrostatic field is zero (E=0) and potential is constant throughout.

Potential of a Charged Conducting Sphere (Outside)

V = kq / r for points outside the charged sphere.

Equipotential Surface

A surface where every point has the same electric potential.

Equipotential Surface Properties

No work is done moving a charge on an equipotential surface; electric field lines intersect it at right angles.

Dielectrics

Insulating materials where charge distribution can be altered by an external electric field.

Polar Dielectrics

Dielectrics where the centers of positive and negative charges do not coincide, resulting in a permanent electric dipole moment.

Capacitance

The capability of a system to store electric charge, defined as C = q / V.

Series Combination of Capacitors

A connection where charge is the same, and total voltage splits across them, given by 1/C_total = 1/C1 + 1/C2 + …

Parallel Combination of Capacitors

A connection where potential difference is the same, and total charge is the sum; C_total = C1 + C2 + …

Energy Stored in a Capacitor

U = (1/2) * C * V^2 = (1/2) * q * V = q^2 / (2C).

Common Potential after Charge Redistribution

The potential achieved when connecting two conductors is given by V = (C1V1 + C2V2) / (C1 + C2).