Question

A dipole is placed in an electric field as shown. In which direction will it move ?
[NEET- <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> 2021]

• A. Towards the left as its potential energy will increase.
• B. Towards the left as its potential energy will decrease.
• C. Towards the right as its potential energy will increase.
• D. Towards the right as its potential energy will decrease.

Answer 1

The correct option is D Towards the right as its potential energy will decrease.

Potential energy of electric dipole in external electric field,

$U=-\overrightarrow{P}\cdot \overrightarrow{E}=-PE\cos \theta$


Angle between electric field and electric dipole is ${180}^{\circ }$.

$\therefore U=-PE\cos {180}^{\circ }=+PE$

On moving towards right, electric field strength decrease therefore potential energy decrease.

Net force on electric dipole is towards right and net torque acting on it is zero.
So, it will more towards right.

Therefore, the correct option is $\left(\text{C}\right)$.