Electric Fields and Forces Lecture Notes

Vocabulary and key concepts regarding electric forces, field intensity, units, and mathematical relationships as described in the lecture notes.

Electric Field

An area around a charge where another charge can experience attraction or repulsion.

Electric Field Intensity

The strength of an electric field, denoted by the symbol $E$, which is a vector quantity.

Direction of Electric Field Intensity

The direction of the electric field intensity is described as being radially outward.

MKS SI Unit of Electric Field Intensity

$N/C$ (Newtons per Coulomb).

CGS Unit of Electric Field Intensity

$D/C$ (Dyne per Coulomb).

FPS Unit of Electric Field Intensity

$lb/c$ (Pounds per Coulomb).

Mathematical formula for Electric Field Intensity

$$E = \frac{F}{q}$$

Base Units of Electric Field Intensity

$$\frac{kg \times m}{A \times s^3}$$

Dimension of Electric Field Intensity

$$MLT^{-3}A^{-1}$$

Relationship between Force ($F$) and Distance ($r$)

Force is inversely proportional to the square of the distance, represented as $F \times \frac{1}{r^2}$.

Torsion Balance

An instrument mentioned in the notes used to determine the strength or forces within an electric field.

Maximum Force calculation

$F_{12} = \frac{Kq^2}{4}$ (calculated for a distance of $r=2$).

Minimum Force calculation

$F_{13} = \frac{Kq^2}{25}$ (derived from a distance of $r=5$, identified in the notes as the minimum force).

Ascending Order of Forces

According to the notes, the order from smallest to largest is $F_{13} < F_{12} < F_{11}$ based on distance denominators.