Question

At what angle between dipole moment and electric field electric dipole remains in stable equilibrium

Answer 1

A a dipole in stable equilibrium, when Electric filed and dipole moment are perpendicular to each other i.e. the angle between them is zero degree and torque will be maximum.

Answer 2

Answer:

The Correct Answer would be Zero Degree. When dipole moment and electric field have 0° angle between them, they would be in stable equilibrium.

Explanation:

We know that, potential energy(U) of a system is:

                               U = -p×E×cosθ            

where, p = electric dipole, E = electric field and θ = angle between electric field and dipole. Now, U would be at equilibrium at two stages. First, when the value of U is highest, Second, when it is lowest. At the lowest value, the equilibrium obtained is stable. Hence, the correct answer would be the one at which we will acquire lowest value of U, that is -pE.

At θ = 0°, Cos θ = 1.

We are getting U = -pE(1) =  -pE

Now, again at θ = 180°, Cos θ = -1

We are again getting U = -pE(-1) = pE

Clearly, at 0°, U is minimum which means it is in stable equilibrium.

Therefore, when Electric filed and the dipole moment acting are basically perpendicular to each other i.e. the angle between them is zero degrees, the state of stable equilibrium would be achieved.