Dielectrics – orientation polarization dependence Orientation polarization in a polar dielectric depends on temperature and the permanent dipole moment p. Which statements are correct? directly proportional to temperature inversely proportional to temperature inversely proportional to square of permanent dipole moment directly proportional to square of permanent dipole moment

Introduction:
Polar dielectrics possess permanent dipole moments. Under an applied electric field, these dipoles tend to align, producing orientation polarization. Thermal agitation resists alignment, and the magnitude of the permanent dipole determines the strength of alignment. Understanding this dependence is important in capacitor dielectrics and microwave materials.

Given Data / Assumptions:

• Low-field, linear response regime.
• Classical Debye model for orientation polarization.
• Uniform temperature and isotropic material.

Concept / Approach:

The Debye expression for orientation polarization P_o is proportional to (n * p^2 / (3 * k * T)) * E in the linear limit. Hence, P_o ∝ p^2 and P_o ∝ 1/T. Larger permanent dipole moments give stronger polarization; higher temperature increases randomization, reducing polarization for a given field.

Step-by-Step Solution:

Verification / Alternative check:

Dielectric constant ε′ for polar liquids decreases with rising temperature (orientation part diminishes), consistent with P_o ∝ 1/T; materials with larger molecular dipoles show larger orientation contributions, consistent with p^2 dependence.

Why Other Options Are Wrong:

Options A, B, C include incorrect statements 1 or 3; only D includes both correct statements (2 and 4).

Common Pitfalls:

Assuming linear proportionality to p rather than p^2; overlooking thermal agitation’s inverse role.

Final Answer:

2 and 4 only