An electric dipole of moment 6×10⁻⁶ C·m is initially parallel to a uniform electric field of 10⁶ N/C. Work required to rotate it through 180° is:

Question

G1 Physics · Accepted Answer

U=-pEcosθ. Rotating from 0° to 180° gives ΔU=pE-(-pE)=2pE=2×6×10⁻⁶×10⁶=12 J.