Question

An electric dipole is placed perpendicular to an infinite line of charge at some distance from it as shown in the figure. Then the dipole

• A. is attracted towards the line charge
• B. is repelled away from the line charge
• C. does not experience a force
• D. is experienced force as well as torque

Answer 1

The correct option is A is attracted towards the line charge

The negative charge of dipole is near the infinitely long, positive line charge. Hence, attraction is of more magnitude than repulsion, as the magnitude of the charges is the same.

From the formula of electrostatic force,

$F_1=\frac{2k\lambda q}{r}$ and $F_2=\frac{2k\lambda q}{r+2l}$

Thus, $F_1>F_2$

Further, the force of attraction and repulsion passes through the centre of the dipole, as shown in the figure. Thus, there is no torque.

Hence, $\left(A\right)$ is the correct answer.