Question

An electric dipole of diploe moment $\overrightarrow{p}$ placed in uniform electric field $\overrightarrow{E}$ has maximum potential energy when angle between $\overrightarrow{p}$ and $\overrightarrow{E}$

• A. $\frac{\pi }{2}$
• B. zero
• C. $\pi$
• D. $\frac{3\pi }{2}$

Answer 1

Answer: (C)

$\text{Step 1: Electric Potential energy of dipole}:$

The potential energy of the dipole is given by the equation,

$U=-\overrightarrow{p}.\overrightarrow{E}=-pE\cos \theta$

Here, $\theta$ is the angle between the dipole moment $\left(\overrightarrow{p}\right)$ and the electric field$\left(\overrightarrow{E}\right)$ as shown in figure.

$\text{Step 2: Condition for maximum Potential energy of dipole}:$

$U$ is maximum when $\cos \theta =-1$ and $U=+pE$

$\Rightarrow \theta =\pi$

Hence, Option(C) is correct.

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