Practice question

**Electric dipole** consists of charges +q and -q separated by 2a, dipole moment p = q·2a, vector from negative to positive, unit C·m. In uniform field E, torque τ = p × E, magnitude τ = p E sinθ, tending to align p with E, potential energy U = -p·E = -p E cosθ. For a conductor, E = (k q/r²) at surface ( r = 0.15 m ). E = 9 × 10⁹ × (6 × 10⁻⁶/(0.15)²) = 2.4 × 10⁶ N/C . Substituting values gives 2.4 × 10⁶ N/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.