Two shorts dipoles (A, B), A having charges ± 2μC and length 1 cm and B having charges ± 4μC and length 1 cm are placed with their centres 80 cm apart as shown in the figure. The electric field at a point P, equi-distant from the centres of both dipoles i $s_____N/C.$

Question

G1 Physics · Accepted Answer

Point P is 40 cm from the centre of each short dipole: r = 0.40 m. Dipole moment of A: p(A) = qℓ = 2×10⁻⁶ × 10⁻² = 2×10⁻⁸ C·m. Dipole moment of B: p(B) = 4×10⁻⁶ × 10⁻² = 4×10⁻⁸ C·m. From the geometry, P lies on the axial line of dipole A and on the equatorial line of dipole B. Axial field of dipole A: E(A) = 2kp(A)/r³. Therefore, E(A) = [2×9×10⁹×2×10⁻⁸]/(0.4)³ = (9×10⁴)/16 N/C. Equatorial field magnitude of dipole B: E(B) = kp(B)/r³ = [9×10⁹×4×10⁻⁸]/(0.4)³ = (9×10⁴)/16 N/C. The two fields are p…

Two shorts dipoles (A, B), A having charges ± 2μC and length 1 cm and B having charges ± 4μC and length 1 cm are placed with their centres 80 cm apart as shown in the figure. The electric field at a point P, equi-distant from the centres of both dipoles i s_____N/C.