Question

Two charges +q and -q are placed at a distance "a" in a uniform electric field. The dipole moment of the combination is 2q $(cos\theta \hat{i}+sin\theta \hat{j})$, where $\theta$ is the angle between the direction of the field and the line joining the two charges.Which of the following statement(s) is/are correct?

• A. The torque exerted by the field on the dipole vanishes
• B. The net force on the dipole vanishes
• C. The torque is independent of the choice of coordinates
• D. The net force is independent of d

Answer 1

Answer: (B), (C), (D)

The correct options are
B The net force on the dipole vanishes
C The torque is independent of the choice of coordinates
D The net force is independent of d

ACCORDING TO THE GIVEN QUESTION , THE GIVEN FIGURE SHOWAS THAT :

THE NET FORCE ON THE DIPOLE IS ZERO.

THE TORQUE DEPENDES ONLY ON THE MAGNITUDE OF FORCE AND THE VALUE OF $d$, AND THE DIRECTION OF THE TORQUE IS DEPEND ON THE DIRECTION OF ELECTRIC FIELD.

SO IT DOES NOT DEPEND ON THE COORDINATES;

SINCE THE VALUE OF NET FORCE IS ZERO SO IT DOES NOT DEPEND ON THE VALUE OD $d$ ;

HENCE THE OPTION B,C,D ARE THE CORRECT OPTIONS.