Electric Charges & Fields
Class 12 · Electric Charges & Fields

Field Lines — Multiple Charges

Two +, two −, quadrupole, three + — switch and watch the line patterns morph.

Run simulation

Key Notes

01

Field at any point = vector sum of fields from each charge.

02

Two equal +q create a 'saddle' point at the midpoint (E=0 there).

03

Quadrupole: alternating ± charges create a 4-leaf pattern with E=0 at center.

04

Lines bunch up where field is strong; spread out where weak.

Formulas

Field superposition

Add fields as vectors.

Important Points

Look for null points: places where E⃗ vanishes by symmetry.

Between two equal +q, midpoint is a null. Between +q and −q, no null on the line.

Field Lines — Multiple Charges notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 12 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.