We have two electric dipoles. Each dipole consists of two equal and opposite point charges at the ends of an insulating rod of length d. The dipoles sit along the x-axis a distance r apart oriented as shown in fig. Their separation `rgtgtd`. The dipole on the left:

Options

A. will feel a force upward and a torque trying to make it rotate clockwise
B. will feel a force upward and a torque trying to make it rotate counterclockwise
C. will feel a force upward and no torque about its center
D. will feel a force downward and a torque trying to make it rotate clockwise

Answer

B

Explanation

Electric field due to right dipole at left dipole is shown. There are `E_(1)` and `E_(2)`, but `E_(1)gtE_(2)` so `F_(1)gtF_(2)` so net force on the dipole is upward. Also `F_(1)` and `F_(2)` will produce anticlockwise torque. Electric field on right dipole due to left dipole are shown. `F_(1)` and `F_(2)` are the forces on this dipole, Net forces will be downward direction also `F_(1)` and `F_(2)` will produce anticlockwise torque.