Electrical Charges and Fields

Electric field lines start from positive charges, Electric field lines end at negative charges, Tangent to field line gives field direction

Electric field lines are imaginary constructs that help visualize electric fields. They start from positive charges, end at negative charges, never cross each other, and the tangent at any point gives the field direction at that point.

Coulomb-meter (Cm)

Electric dipole moment p = q × d, where q is charge and d is separation distance. Therefore, its unit is Coulomb × meter = Cm.

E = p/(4πε₀r³)

For a dipole at broad-on position (perpendicular bisector), when r >> l, the electric field is E = p/(4πε₀r³), where p = 2lq is the dipole moment.

Total charge inside the surface

Gauss's law states that electric flux φ = q/ε₀, where q is the total charge enclosed by the Gaussian surface. The flux depends only on the enclosed charge, not on charges outside or the surface shape/area.