In electronic polarization the dipole is _____, while in orientational polarization it is _____.

induced; already present and then aligned

Which pair of polarizabilities is correct?

alpha_e = 4 pi eps0 R^3, alpha_d = p0^2/(3kT)

alpha_e = p0^2/(3kT), alpha_d = 4 pi eps0 R^3

Interfacial polarization arises from:

Mobile charges piling up at grain boundaries or electrodes

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Polarization types; electronic vs orientational

Short answer

Polarization types: electronic (electron-cloud shift), ionic (ion displacement), orientational (dipole rotation), and space-charge (interfaicial). Electronic occurs in all materials, nearly temperature-independent, and responds up to UV/optical frequencies. Orientational occurs only in polar molecules, decreases with temperature as 1/T, and operates only up to radio/microwave frequencies.

What are different types of polarization in dielectric medium? How do electronic polarization differ from orientational polarization?

Polarization is the displacement of bound charges in a dielectric under an electric field, giving a net dipole moment per unit volume, $P = N\alpha E_{loc}$ .

Types of polarization

Electronic polarization: the electron cloud of each atom shifts opposite to the field, while the nucleus shifts slightly with it. It occurs in all materials. $\alpha_e = 4\pi\varepsilon_0 R^3$ , independent of temperature.
Ionic polarization: in ionic solids (NaCl, KCl), positive ions move along the field and negative ions against it, changing the bond lengths and creating a net dipole moment.
Orientational (dipolar) polarization: polar molecules (H₂O, HCl, nitrobenzene) have permanent dipoles pointing randomly. The field tends to align them, and thermal motion opposes this, so $\alpha_d = p_0^2/(3kT)$ .
Interfacial (space-charge) polarization: mobile charges pile up at grain boundaries, impurities or electrodes, as in polycrystalline and multiphase materials.

 No field:   (+)    E ->   ( +)->   electron cloud
  atom       (o)           (o )     shifts left,
                                    nucleus right
 Polar molecules:  /  \  |  -  ->  -> -> ->  aligned

Electronic vs orientational polarization

Point	Electronic	Orientational
Mechanism	Shift of electron cloud	Rotation of permanent dipoles
Materials	All (gases, liquids, solids)	Polar molecules only
Polarizability	$\alpha_e = 4\pi\varepsilon_0R^3$	$\alpha_d = p_0^2/3kT$
Temperature effect	Independent of $T$	Decreases as $1/T$
Frequency limit	Up to ~ $10^{15}$ Hz (optical)	Up to ~ $10^{9}$ – $10^{11}$ Hz
Size	Small	Large (water $\varepsilon_r \approx 80$ )
Dipole before field	Not present (induced)	Already present
Loss	Very low	Can be high near relaxation

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