Electric Charges & Fields

Practice flashcards covering the fundamental concepts, laws, and formulas of electric charges and fields based on NCERT Class 12 Physics.

Electric Charge

A fundamental property of matter that can be positive ($+$) or negative ($-$), having the SI unit of Coulomb ($C$).

Quantisation of charge

The principle stating that charge exists in discrete packets defined by the formula $q = \neq ne$, where $n = 0, 1, 2, 3 …$ and $e = 1.6 \times 10^{-19}\,C$.

Conservation of charge

A property of matter stating that charge can neither be created nor destroyed.

Coulomb's Law

A law stating that the force between two charges is directly proportional to the product of charges and inversely proportional to the square of the distance between them, expressed as $F = \frac{1}{4πε_0} \frac{q_1 q_2}{r^2}$.

Electric Field ($E$)

The region around a charge in which another test charge experiences a force, defined as $E = \frac{F}{q_0}$ with dimensions $[M L T^{-3} A^{-1}]$.

Electric Field Lines

Imaginary lines used to represent the electric field that start from positive charge, end at negative charge, and never intersect each other.

Electric Dipole

A system of two equal and opposite charges, $+q$ and $-q$, separated by a small distance $2a$.

Dipole Moment ($p$)

A vector quantity calculated as $p = q \times 2a$, with a direction pointing from $-q$ to $+q$.

Electric Flux ($ϕ$)

A measure of the number of electric field lines passing through a surface, calculated by $ϕ = EA \tan(\theta)$ with a scalar quantity and SI unit $N\,m^2/C$.

Gauss's Law

The law stating that the total electric flux through any closed surface is equal to the net charge enclosed ($q_{enc}$) divided by $ε_0$, shown as $∮ \mathbf{E} ⋅ d\mathbf{A} = \frac{q_{enc}}{ε_0}$.