In a medium of dielectric constant K, the electric field is E. If $ε_0$ is permittivity of the free space, the electric displacement vector is
Answer & explanation
Correct answer: option 4
The electric displacement field is a vector valued D that accounts for the effects of bound charges within materials. In general D is given by
$D = ε_0 E + P$
When E is electric field, $ε_0$ the vacuum permittivity and P the polarization density of the material.
In most ordinary terms
$D = ε_0E$
When dielectric is present $ε = K ε_0$
$∴ D = Kε_0 E$