An electric dipole has charges ±2 μC separated by 0.5 μm. It is placed between capacitor plates separated by 0.5 mm with potential difference 5 V. If the dipole is rotated by 30° from the electric-field direction, the torque magnitude is:
Options

Question

An electric dipole has charges ±2 μC separated by 0.5 μm. It is placed between capacitor plates separated by 0.5 mm with potential difference 5 V. If the dipole is rotated by 30° from the electric-field direction, the torque magnitude is:

Options

G1 Physics · Accepted Answer

Electric field between the plates is E = V/d = 5/(0.5×10⁻³) = 10⁴ V/m. Dipole moment: p = qℓ = (2×10⁻⁶)(0.5×10⁻⁶) = 1×10⁻¹² C·m. Torque on a dipole: τ = pE sinθ. With θ = 30°: τ = (1×10⁻¹²)(10⁴)(1/2) = 5×10⁻⁹ N·m. Correct option: A.