Class 12PhysicsChapter 1: Electric Charges and Fields

Key Formulas

Summary of key formulas for Electric Charges and Fields.

Concept	Formula
Coulomb's Law	$F = \dfrac{1}{4\pi\varepsilon_0}\cdot\dfrac{q_1 q_2}{r^2}$
Electric field (point charge)	$E = \dfrac{1}{4\pi\varepsilon_0}\cdot\dfrac{q}{r^2}$
Dipole moment	$\vec{p} = q \cdot 2a\,\hat{d}$
Torque on dipole	$\tau = pE\sin\theta$
Gauss's Law	$\oint \vec{E}\cdot d\vec{A} = \dfrac{q_{\text{enc}}}{\varepsilon_0}$
Infinite plane	$E = \dfrac{\sigma}{2\varepsilon_0}$

1.5 Gauss's Theorem

Gauss's law and its applications: infinite line charge, plane sheet, and spherical shell.

9.1 Refraction at a Spherical Surface

Refraction formula at a spherical surface separating two media.