1uC and -1uC are placed at a distance of 5 cm forming a dipole. What is the amount of torque required to place the dipole perpendicularly to an electric field of 3*105 N/C?
A. 5*10-3 N. m
B. 15*10-3 N. m
C. 1*10-3 N. m
D. 10*10-3 N. m
Answer:B
1uC and -1uC are placed at a distance of 5 cm forming a dipole. What is the amount of torque required to place the dipole perpendicularly to an electric field of 3*105 N/C?
A. 5*10-3 N. m B. 15*10-3 N. m C. 1*10-3 N. m D. 10*10-3 N. m
Explanation: Dipole moment of the dipole = 1*10-6*5*10-2 C. m=5*10-8 C. m. Given the electric field-intensity is E=3*105 N/C. Therefore required torque will be p*E*sinθ where θ is the angle between the electric field and the dipole moment = 90 degrees. Therefore torque required in this case will be 5 *10-8*3*105*sin 90 N. m=15*10-3 N. m.