## Pages

### Key Equations

 Coulomb’s law F⃗ 12(r)=14πε0q1q2r212rˆ12 Superposition of electric forces F⃗ (r)=14πε0Q∑i=1Nqir2irˆi Electric force due to an electric field F⃗ =QE⃗ Electric field at point P E⃗ (P)≡14πε0∑i=1Nqir2irˆi Field of an infinite wire E⃗ (z)=14πε02λzkˆ Field of an infinite plane E⃗ =σ2ε0kˆ Dipole moment p⃗ ≡qd⃗ Torque on dipole in external E-field τ⃗ =p⃗ ×E⃗