Polar molecules are the molecules:

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

The electric field at a point on the equatorial plane at a distance \(r\) from the centre of a dipole having dipole moment $\stackrel{}{}$\(\overrightarrow{P}\) is given by:
(\(r\gg\) separation of two charges forming the dipole, \(\epsilon_{0} =\) permittivity of free space) 
1. \(\overrightarrow{E}=\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\) 

2. \(\overrightarrow{E}=\frac{2\overrightarrow{P}}{\pi \epsilon _{0}r^{3}}\)

3. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{2}}\)

4. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\)

An electric dipole is placed at an angle of \(30^\circ\) with an electric field intensity \(2\times10^5~ \text{N/C}\). It experiences a torque equal to \(4 ~\text{N-m}\). The charge on the dipole, if the dipole length is \(2~ \text{cm}\), is:

Three-point charges + q, -2q and +q are placed at points (x=0, y=a, z=0), (x=0, y=0, z=0) and (x=a, y=0, z=0), respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are:
 

A dipole of moment $\overrightarrow{p}$ is placed in uniform electric field $\overrightarrow{E}$. The torque acting on it is given by:
1. \(\vec{\tau }=\vec{p}.\vec{E}\)
2. \(\vec{\tau }=\vec{p} \times\vec{E}\)
3. \(\vec{\tau }=\vec{p}+\vec{E}\)
4. \(\vec{\tau }=\vec{p}-\vec{E}\)

The electric field at the equator of a dipole is \(E.\) If the strength of the dipole and distance are now doubled, then the electric field will be:

A point \(Q\) lies on the perpendicular bisector of an electric dipole of dipole moment \(p.\) If the distance of \(Q\) from the dipole is \(r\) (much larger than the size of the dipole), then the electric field at \(Q\) is proportional to:
1. \(p^{2}\) and \(r^{-3}\)
2. \(p\) and \(r^{-2}\)
3. \(p^{-1}\) and \(r^{-2}\)
4. \(p\) and \(r^{-3}\)