A dipole is placed in an electric field as shown. In which direction will it move ? 

CONCEPT:

The potential energy of electric dipole in an external electric field is written as

\(U = - \overrightarrow P .\overrightarrow E \) -----(1)

Where P is the dipole and E is the electric field.

CALCULATION:

Using equation (1) we get;

\(U = - \overrightarrow P .\overrightarrow E \)

⇒ U = – PEcosθ 

The angle between the electric field and the electric dipole is 180°, therefore,

U = –PEcos180°

U = + PE

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

The net force on the electric dipole is towards the right and the net torque acting on it is zero.

So, it will move towards the right.