16. Three charges of magnitude 10 C are placed at the three vertices of an equilateral triangle of side 20 cm. Calculate the electric field at the centre of the triangle. Ans. Zero 17. Calculate the maximum torque produced on an electric dipole with moment 4 x 10-5 C-m, placed in an electric field of 180N/C. Ans. 7.2 103 N-m 18. An electric dipole of length 2 cm, when placed with its axis making an angle of 60 with a uniform electric field, experiences a torque of 83 Nm. Calculate the potential energy of the dipole, if it has a charge 4 C. Hint: pE sin 0 and PE (CBSE 2014) - PE cos 0 PE P cos 0 psin 0 -83 x 1 -83 =-tcot 0= 3 3 -83 Ans. Joule 3 19. The electric force experienced by a charge 10 nC is 2x 105 Newton. Calculate the electric field at the position of the charge.