Electromagnetism: Electric Fields, Dipoles, and Continuous Charge Distributions

Vocabulary flashcards covering core concepts from the electromagnetism lecture, including electric fields of point charges, dipoles, field line properties, and continuous charge distributions.

Electric Field

A vector field with a direction and magnitude present everywhere in space caused by a source charge, even when no test charge is present.

Source Charge

A point charge that creates an electric field throughout all locations in space, pointing away from it if positive and toward it if negative.

Electric Dipole

A system composed of two charges separated by a distance that possess equal but opposite charges.

Permanent Dipole

An inherent dipole structure found in certain molecules, such as a water molecule.

Induced Dipole

A dipole created when a charged object is brought near another object, resulting in attraction by polarization.

Electric Dipole Moment ($\mathbf{p}$)

A vector pointing from the negative charge to the positive charge whose magnitude equals the product of the charge magnitude and the separation distance, indicating the dipole's spatial orientation.

Far Field of a Dipole

The electric field produced at a distance from a dipole along its axis or perpendicular axis, which depends inversely on the distance cubed ($r^3$).

Electric Field Lines

Continuous visual field lines that originate on positive charges, terminate on negative charges, and never cross.

Tangent to an Electric Field Line

A geometric line tangent to a field line at any point that specifies the direction of the electric field at that location.

Electric Field Line Spacing

A visual representation of field strength where closely spaced lines indicate a stronger electric field and widely spaced lines indicate a weaker field.

Linear Charge Density ($\lambda$)

The quantity of electric charge per unit length along an object such as a uniformly charged rod, defined by $\lambda = \frac{Q}{L}$.

Surface Charge Density ($\eta$)

The quantity of electric charge per unit area on a sheet or plate, represented by the Greek letter eta ($\eta$) and defined as $\eta = \frac{Q}{A}$.

Infinitesimal Charge ($dq$)

A tiny element of charge on a segment of an extended object, calculated for a 1D rod as the linear charge density multiplied by an infinitesimal length ($dq = \lambda\,dx$ or $dq = \lambda\,dL$).

Superposition of Electric Fields

The method of determining the net electric field by summing the vector contributions of all individual point charges or infinitesimal charge elements.