20. HCl molecule with dipole moment 34x100 C-m is held at 60 with an electric field of 2.510 N/C (a) Calculate the torque on HCI. (b) Calculate maximum torque on HCL. Ans. (a) 7.35 x 10-26 N-m, (b) 8.5x10-26 N-m 21. How much work would be done on a dipole with moment 2.5 x 106 C-m, placed in electric field of magnitude 2102 N/C to change the orientation from zero to 180? Ans. 103 Joule 22. Four charges +q, -q, +q-q are arranged as shown in Fig. 2.49. If the magnitude q = 1.6 103 C and d=4 cm, 200 cm- Fig. 2.49 (1) calculate the quadrupole moment of quadrupole so formed. (ii) calculate the electric field at a point P, 200 cm away from the quadrupole combination as shown in figure.