In a medium of dielectric constant $K$,the electric field is $\vec E$. If $\varepsilon_0$ is the permittivity of free space,the electric displacement vector is:

Due to which phenomenon does the surface charge density arise on the surface of a dielectric slab when it is placed in a uniform electric field?

What is the dimensional formula for the intensity of polarization?

Which of the following statements is false in the case of polar molecules?

$Assertion \; (A)$: Non-polar materials do not have any permanent dipole moment.
$Reason \; (R)$: When a non-polar material is placed in an electric field,the centre of the positive charge distribution of its individual atom or molecule coincides with the centre of the negative charge distribution.
In the light of the above statements,choose the most appropriate answer from the options given below:

When a dielectric is placed in an external electric field,the electric field inside the dielectric is