Error Analysis — Common Mistakes in Electrostatics — Notes | NoteTube

#	Mistake	Why Wrong	Correction
1	E = 0 inside any sphere	Applies only to conductors	E = 0 only inside conductors; inside insulating sphere E = kQr/ $R^{3}$
2	Axial and equatorial dipole fields are equal	They differ by factor of 2	E_axial = 2kp/ $r^{3}$ ; E_equatorial = kp/ $r^{3}$
3	When battery is disconnected and dielectric inserted, V stays constant	V = Q/C; if C increases and Q is fixed, V decreases	V' = Q/C' = V/K
4	Series capacitors have same voltage	Series → same charge, NOT same voltage	Parallel → same voltage; series → same charge
5	Capacitance depends on charge placed on it	Capacitance is a geometry property	C = ε_{0}A/d; independent of Q or V separately
6	Work done moving charge along equipotential is non-zero	Potential difference = 0, so W = q $\Delta V$ = 0	W = 0 on equipotential surface always
7	Dipole potential on equatorial line equals V = kp/ $r^{2}$	Contributions from +q and −q cancel exactly	V_equatorial = 0 at all equatorial points
8	Coulomb's law applies to extended charge distributions directly	Coulomb's law is for point charges only	For distributions, integrate or use Gauss's law
9	Electric field lines can cross	If they crossed, two directions of E at one point — impossible	Field lines NEVER cross
10	Larger capacitor in series stores more energy	Same Q; U = $Q^{2}$ /2C → smaller C stores more	In series: smaller C stores more energy